[narrator]
Familiar, yet full of surprises. Dolphins paying a visit and bear islands. Polar ice meets a mini Sahara. All this is the Baltic Sea. In the far north,
between Finland and Sweden, lies a labyrinth of islands. There, the sea is so low on salt, one encounters pike. And in the winter,
everything turns to ice. The third episode takes us
to the Gulf of Bothnia, roughly the same size as Slovakia, yet the least known region
of the Baltic Sea. The Gulf of Bothnia is frozen over
at the end of February. A white ocean, roughly 300 kilometers long and 150 kilometers wide. The ice shield, up to one meter 20 thick, covers the entire north of the Baltic Sea. But one animal makes it through. The ringed seal
keeps breathing holes free. After common seals and gray seals, it is the third type of seal
in the Baltic Sea. Roughly 10,000 animals
live in the northern region. With their strong claws
on their front fins, they regularly scrape out breathing holes and extend them
to prevent them from freezing over. Ringed seals need the ice to survive. Because this is their nursery. The baby was born in the middle of winter in a protected cave, which the mother dug out
of a snowdrift in the pack ice. With access to the sea, of course, so that the mother can suckle her baby
after the hunt. She has laid out an entire system of exits in the icy subterranean labyrinth. It is still not entirely clear just how she finds her way around there. Ringed seals can dive
for around three-quarters of an hour in depths of up to 300 meters
to hunt for fish. But they too have to breathe some time. Unlike in the Arctic, where ice bears and polar foxes lurk, ringed seals are relatively safe
on the Baltic ice. At the most, a sea eagle with a wing span
of two and a half meters and strong claws could grab a baby seal. This is too big for him. It still flees to be on the safe side. The eagle has other prey
in its sights anyway. He's after a herring gull, which he corners and causes to panic. [gull cries] Until it finally spits out the fish that it has just caught. [gull cawing] Tenacity and in-flight acrobatics eventually lead to the desired result. When the sun goes down
in the winter months, it conjures colorful light games
in the Baltic Sea sky. Northern lights glow when solar winds meet with the Earth's atmosphere. Sometimes, the cosmic phenomena
appear for hours. [whooshing] But at times they disappear
within mere minutes. The northern part of the Baltic
is iced over from mid-October right up to May. In the Gulf of Bothnia, the salt content registers
just half a percent. This is why the water freezes more quickly than in other regions of the Baltic Sea. Many river flow into the sea here and sweeten it. Like the 400 kilometer-long Tornio, probably Europe's longest natural river. Just 80 kilometers south
of the Arctic Circle and close to the estuary, it forms the border
between Sweden and Finland. The rapids of Kukkolaforsen do not freeze over in the winter either. The river therefore remains
free from ice in certain places, even at temperatures
up to minus 30 degrees. That's why the otter can hunt here and how he can even live
in this icy region. His fur comprises around 50,000 hairs per square centimeter, more than 400 times more
than a human being. This protects the otter from cold
and moisture in the icy water. Under the ice,
he can dive for long distances and remain underwater
for five to eight minutes. He needs open water to draw breath. Here on the River Tornio, he doesn't have to keep
the air holes open himself. As he loses a lot of warmth
during the hunt, despite his dense fur, the exuberant animal needs
up to a kilogram of food daily, fish, crabs and other aquatic animals. Thanks to the rapids, yet another diver
lives close by the Arctic Circle. The white-throated dipper. After a short dive, it returns to the ice
with caddisfly larvae. While the otter rolls around in the snow
to dry his fur, it grabs hold of the next larvae that it skilfully removes
from its protective pouch and gobbles it down. The diving songbird and the restless water marder both find food in the cold season
in the River Tornio... that soon meets
in a delta full of islands, connected with one another
in the winter by the solid ice. It is the northern end of the Baltic Sea and the south of Lapland. A landscape characterized by open, coniferous forests. The home of reindeer. Close to the Baltic coast, the snow in winter is not as high
as it is further inland. This makes life easier for the deer
than it was in the mountains, scraping food free with his wide hooves, primarily lichens and moss. Like snow shoes,
the hooves distribute the weight and prevent them from sinking too deeply. They are not wild reindeers, but the Sámi's half wild,
roving domestic animals. They have markings on their ears or wear collars
that show who the owner is. Each winter, the reindeer breeders bring their herds to the lower levels
of the coast. They have to search for food themselves. They often take off
across the ice of the Baltic from island to island
and pass by settlements on their search for new feeding grounds. They even scratch around under birdhouses for seeds in people's front gardens. But the deer remain timid. Whenever a sledge comes close, they disappear in the vastness
of the coniferous forests on Lapland's coast. Three hundred kilometers south of Lapland lies the Kvarken archipelago. Here, too, the Baltic is covered in ice. And in between,
deposits from primeval glaciers, corrugated like enormous washboards, jutting out from the sea. The skerry sea of Kvarken is known to be especially rich in fish. This is why Finland's west coast
is so popular even in winter. Vesa Heinonen and Jukka Viita
have laid out some bait. A white-tailed sea eagle scrutinizes each step they make. They reopen the hole in the ice
with a shovel and a drill. Nothing new for the eagle. Ice fishing in temperatures
of below 20 degrees is a national sport in Finland. The two men bring in the long twine on which they'd attached
a lure and a net. And pull out a pike,
out of the Baltic Sea. The eagle has to be patient. It's not his turn until the men leave after a successful bout of fishing. [eagle cawing] Like almost everywhere else,
due to pollutants and hunting, sea eagles almost became extinct in Finland, too, in the 1970s. A few had managed to survive
in the Kvarken archipelago. [birds cawing] Nowadays, in the summer, around 35 couples breed here. [eagles cawing] Sometimes in the winter, as many as 300 eagles have been spotted. But they cannot hunt
on the frozen-over Baltic Sea. They would normally migrate
to ice-free waters further south. Leftovers from the ice anglers and especially created food points help the eagles and other birds
through the winter. [birds angrily squawking] And still they quarrel. In most places, the Kvarken archipelago is completely frozen over. But sometimes, currents between the thousands of islands
keep water areas open. In these areas, dozens of swans
spend the winter, as they find their main source
of food here, water plants. Mute swans, and the slightly smaller whooper swans. After being hunted in the 1950s, Finland's national bird
almost became extinct. [swans honking] Today, in the spring, their trombone-like calls
can once again be heard. [swans honking] Pairs stay together all of their lives. [swans honking] They renew their bond each spring with a synchronized
expressive dance on the water. [honking continues] In the meantime, almost 7,000 whooper swan pairs nestle in Finland. In the past decades, the mute swans first settled in numbers in the north of the Baltic Sea. At the end of March,
the first frozen surfaces break apart further out to sea. Near to the coast, bays and lagoons are still iced over, as are many rivers. As of the middle of April, temperatures rise above freezing point and the Kvarken archipelago transforms into a mosaic of islands,
lakes and swamps. And a great migration begins. Most of the fish
in the Kvarken archipelago are of the freshwater variety. They can only survive because there is so little salt
in the north of the Baltic Sea. For their propagation however,
they require pure freshwater. This is why perch and roach leave the sea and head for the river estuaries, which are now full of melt water,
to spawn. Pikes follow them. The perch immediately position
their spiny dorsal fins to appear larger
in the face of these predators. Pikes, too, spend most of the year
in Baltic seawater, but in the spring they leave
for the rivers or lakes behind the coastal line to spawn. This narrow channel connects
one of these lakes with the sea. When the sun goes down,
the freshwater migration begins. The fish masses attract hunters. [birds squawking] They come from the air. And lurk on the water, great crested grebes, gulls, sea swallows. Even large, more than a meter-long pikes, worm their way
through the stony bottleneck to their spawning grounds. They attempt the passage
with a strong tail stroke. Those that go astray in the process
don't make it, so close to their goal. Those that make it to the other side
are already expected. [bird cawing] Sea eagles and gulls. Crows and cranes. The ringed eagle has known this place
for more than 20 years. Many of the fish are exhausted, they die or are at least easy prey. Even for cranes, who normally live
from seeds and insects, but here can tear apart a big pike
with their sharp beaks. The time of spring feelings
ends fatally for many. Despite all of their losses, the propagation of sufficient fish
is always ensured. This is extremely dangerous for male pike. As the significantly bigger females are also quite keen on
smaller conspecifics as prey. Fortunately for the males, the females have a bite inhibition
whilst mating. Several males court one particular her. But only one of them comes into play
per spawning procedure. The complete pairing takes hours. Pikes don't lay their eggs in one go. They do this in portions and in surges, altogether, often more than 100,000. They adhere to leaves. This way, they are not washed away and in ten days, they develop into larvae in the oxygen-rich water. After just a few weeks, the mini-pikes have grown several centimeters in length. The conditions are perfect. The shallow waters are full of nutrients and they warm up quickly
in the spring sunshine. A good day for a swim. And some prove just how contagious sheer joy can be. [cranes cawing] OK, cranes dance the whole year long, but in the spring, they go into overdrive. Then, dancing together becomes a ritual, comprising jumping, wing-flapping
and calling in a duet. A sign of cohesion
for the coming breeding season in the Kvarken archipelago. Here, one can see
a very special phenomenon that also occurs in the Baltic Sea,
land uplift. Until up to around 10,000 years ago, a three kilometer-strong
ice shield covered the area. The weight of which used to push
the Earth's crust into the depths below. Then the glaciers melted, and the ground is still re-expanding. Up to today, it rises at a rate of roughly one centimeter annually. In a hundred years,
we are talking of almost a meter and then these boathouses
will be on dry land. In many parts of the Kvarken archipelago, harbors have to be continuously moved, as due to the ground elevation, they have become unsuitable for shipping. This is why only special boats with a low draught navigate these waters. In two and a half thousand years, the islands will have risen
so far out of the Baltic Sea, that we'll be able to walk
from Finland to Sweden. In the forests along the northern Baltic, moose are not exactly a rarity. Nevertheless, in 2015, one of them hit the headlines in Finland. A moose cow died
when it collided with a car. The consequence, the calf lost its mother. As an orphan, it would have
no chance whatsoever. But it is brought to Markku Harju, who takes care of injured animals. He calls the moose calf Mervi and Mervi soon gets to wander
around Markkus' property, as free as a bird. Before long,
the two of them are inseparable. Bringing up moose babies
with a bottle rarely works. It's difficult to obtain the correct milk. Mervi suffers from acute diarrhea. But the little fellow is tough. And the two of them
are enjoying the joint summer break. Mervi seems to really like the reeds on the Baltic Sea beach. The story of the two friends
moves the whole of Finland and Mervi becomes a little star. For quite some time, it remains unclear whether the moose calf will make it. But in the spring of 2016, Markku takes this photo. One of Europe's rarest animals also lives in the Finnish forests. At first sight,
it looks just like a common squirrel. In Europe, they can only be found in Estonia and Finland. The animals mostly spend the day in abandoned woodpecker holes. In the spring however, they are also diurnal
in their own special way. By using skin flaps, flying squirrels are able to fly distances of up to 35 meters. It's mating time and the flying squirrels are looking for suitable partners. The female has already found
a nursery for her offspring. She rubs her scent from cheek glands
onto branches. And sets marks with urine. Interested males
give this cocktail a good sniff. And if he likes the smell... he really is after her. After four weeks, between two and four
young flying squirrels will be born in the protection
of the tree hollow. The Kvarken archipelago
and its thousands of islands is an ideal breeding ground for birds. Especially for those
who breed on the ground. As predators like foxes find it difficult in so much water... to steal a small goose or to pilfer an egg from a gull's island nest. But when the redshank issues a warning, it means something. A hooded crow is approaching
a mew gull's nest. While one parent broods, the other is on sentry duty. This is also necessary. Hooded crows are skillful nest robbers, that never miss a moment of negligence. They're stubborn too. [birds cawing] The other gull arrives in support. Hardly banished, the crow returns and attacks once again. [angry cawing] Until the bird is chased away by an entire squad of gulls... while the first chick hatches in the nest. In the end,
the crow actually is successful. And clears off into the bushes
with her prey, where the gull cannot follow. Now, even the clamoring of the gulls
is to no avail. In the meantime, the cranes
also have offspring in their nest, safe from foxes
on an island in the swamps. The chicks still hide
in the warm plumage of the parents. They don't need to go far to find food. There are insects all around the nest. Like this dragonfly larvae. And another. The chick is but a few hours old and has an appetite for four. Idyllic family life, close up and in a way very rarely seen. While the parents keep the nesting grounds
in their sights, they don't see that the older chick is maltreating its younger sibling. Sometimes the small bird
is crowded out of the nest, as if a competitor. Despite there being enough to eat. When small cranes grow in size, they search for food together
with the parents. Then they all wade through the swamps and should the water get too deep, the stalking birds become swim birds. Just like the swan family. From the flat world
of the Kvarken archipelago and Finland's last outpost, it is no more than roughly
20 kilometers across the sea. Then, distinctive rocks
protrude on the Swedish side. Some are 150 meters tall. Many consist of red granite, which is typical of the region. The place is called Höga Kusten. The so-called "High Coast"
is full of deep canyons. Tranquil mountain lakes and moors that lay high above the Baltic Sea. Brown bears live here. A male has picked up the scent of a female bear and is following her. In the summer,
bears happily cool off in moor lakes. But as they are mostly loners, greetings can be quite unfriendly. [bears roaring] Right next door, someone is adamant the territory is his. [bird squawking] A red-throated diver. The male bear has had enough. She was probably not yet ready. At last, peace falls over the moor. Time to go diving undisturbed... for fish or fresh lily pads. A small red-throated diver swims, full of expectation, to his parent. And while his chick sibling
makes do with an insect, he is served with a big, fat, tasty fish. Another female bear appears. The male bear picks up her scent, an enticingly odorous trail. It seems as though she is willing to mate. When the two meet,
things move pretty fast and furious. With no growling nor snarling. At the beginning of next year,
she will give birth. We mostly talk here
of two to three per litter. And soon, each of them go their own separate ways in the moors of the Höga Kusten, high above the Baltic Sea. Nowhere else
is the land uplift as prominent as it is here
in the Skuleskogen National Park. This is where the Earth's crust
was pressed down deepest by the weight of the glaciers. After the ice melted, these screes once formed
the Baltic Sea shore. Since then, they have risen
higher than anywhere else. The current shores are around
200 meters deeper and evoke the impression
of how the cairns above must have looked 9,000 years ago. Agne Säterberg is a nature scout in Skuleskogen National Park. He once roamed through the forests
and hunted moose. In the meantime,
he no longer follows them with a rifle. The photographer is still impressed
by Sweden's national animal. One should always be alert of moose. They appear cute, slow and cozy. But watch out when they feel harassed. Keep well away from a raging moose. Upset or angry moose cows have been known
to trample people to death. But this one allows another photo. Agne is satisfied. In the skerry garden,
off of the High Coast, lies another work of land uplifting. The island of Trysunda
evolved out of three islands. The villages on the skerries were once only inhabited in the summer. Fishermen used to sail
from here to catch herrings. To this day, the Baltic off the High Coast
is full of fish. This attracts several seabirds
to the skerries. Today, on the abraded islands, western curlews rest. And eider ducks breed. Surprisingly, many Swedes don't know of the attractive drake at all. The main reason being
that they only come in spring for the mating season on the Höga coasts. [birds squawking] Up to ten males then compete
for the approval of one female, who has an inconspicuous plumage. Quite the opposite of the males
in their magnificent frocks, who, once successful, immediately leave the coast
behind them again. But their cooing love calls
can still be made out. [birds cooing] The females lay their eggs in hollows in the scree of the skerries, that they have upholstered
with the finest downy feathers. These are acknowledged
to keep the birds especially warm. Four weeks later
and the chicks have hatched. Their mothers soon lead them out
on to the sea. Often, several duck parents
with their flocks of chicks form a giant kindergarten. The little ones can swim almost
immediately after hatching. And dive, too. And it's not that easy
to remain underwater, when the air in the feathers
keeps tugging the bird upwards. [bird squawks] But with a bit of practice,
it gets better and better. From the very beginning,
the youngsters have to search for their food themselves whilst diving. Little fish, crabs, and later, mussels on the seabed - the staple diet of the eider ducks. The only slightly salted water is fed in the north of the Baltic Sea to this day from glaciers, many of which lay off
Sweden's border with Norway. Here is the source
of countless smaller streams that unite to become ever bigger rivers and surge toward the Baltic coast. The reindeer spend the warm season on the plateaus of Lapland. They move upwards, to the cooler regions to escape the mosquito plague
of a Scandinavian summer. The River Tornio also has its source
in a small glacier in Lapland and flows from there to the estuary and the Baltic Sea. In the summer, the rapids of Kukkolaforsen are a popular rafting area. The untamed river
has more attractions to offer. It is the most important salmon river that flows into the Baltic. Fishermen are waiting everywhere
for the salmon. Everyone has his own method
how to catch one. Some use rod and line. Others use landing nets. At one point,
stocks almost collapsed entirely. Today, thanks to strict regulations, once again hundreds of thousands of salmon aim for the spawning grounds
at the River Tornio, where in the summer, just 80 kilometers from the Arctic Circle, the sun barely sets. And where in the estuary delta
of the river, moose make their way along the shore
of a unique sea. The youngest in the world, with salty water in the west and fresh water in the north-east. The Baltic Sea, a child of the last Ice Age.
