"NIGHTLY NEWS" WITH LESTER HOLT. >>> GOOD EVENING. WELCOME. IT IS A TRAGEDY STEEPED IN IRONY. WHAT OFFICIALS NOW PRESUME TO BE BE THE DEATHS OF AT THE FIVE PASSENGERS ON AN UNDERSEA SIGHTSEEING TRIP TO THE RESTING PLACE OF ANOTHER DISASTER. THE "TITANIC." TODAY THE COAST GUARD ANNOUNCING A REMOTELY OPERATED UNDERWATER VEHICLE LOCATED DEBRIS ON THE OCEAN FLOOR. THE COAST GUARD SAYS IT'S CONSISTENT WITH A CATASTROPHIC IMPLOSION OF THE SMALL VESSEL. THE TAIL CONE FOUND JUST 1,600 FEET FROM THE "TITANIC" SHIPWRECK. THE SUB'S TITANIUM HULL SUCCUMBING TO THE CRUSHING DEPTH OF MORE THAN TWO MILES BENEATH THE SURFACE. THE SUB OPERATOR, OCEANGATE EXPEDITIONS, IN A STATEMENT SAYING, OUR HEARTS ARE WITH THESE FIVE SOULS AND EVERY MEMBER OF THEIR FAMILIES. BUT THE TRAGEDY ALREADY FUELING DIFFICULT QUESTIONS ABOUT THE PURSUIT OF EXTREME ADVENTURES AND THE COST AND DEMAND ON OTHERS WHEN THEY GO WRONG. TOM COSTELLO HAS LATE DETAILS. >> Reporter: HEARTBREAK IN THE NORTH ATLANTIC AFTER FOUR DAYS OF SEARCHING FOR THAT MISSING MINI SUB NAMED "TITAN" AND THE FIVE PEOPLE ONBOARD, THIS MORNING A CANADIAN DEEP SEA ROBOT SPOTTED DEBRIS FROM THE SUB 1,600 FEET FROM THE WRECKAGE OF THE "TITANIC," VET DESTINATION IT WAS HEADED FOR ON SUNDAY. >> THE DEBRIS IS CONSISTENT WITH THE CATASTROPHIC LOSS OF THE PRESSURE CHAMBER. >> Reporter: CATASTROPHIC IMPLOSION IN THE EXTREME PRESSURE AT NEARLY 13,000 FEET BELOW SEA LEVEL. >> THE SIZE OF THE DEBRIS FIELD IS CONSISTENT WITH THAT IMPLOSION IN THE WATER COLUMN. >> Reporter: IN A STATEMENT, OCEANGATE SAID OUR HEARTS ARE WITH THESE FIVE SOULS. WE GLEEFB THE LOSS OF JOY AND LIFE THEY BROUGHT TO EVERYONE THEY KNEW. STOCKTON RUSH, THE FOUNDER AND CEO OF OCEANGATE. BILLIONAIRE ADVENTURER HAMISH HARDING, FRENCH SUB AND "TITANIC" EXPERT PAUL-HENRI NARGEOLOT. WEALTHY BRITISH PAKISTANI BUSINESSMAN SHAHZADA DAWOOD AND HIS 19-YEAR-OLD SON SULEMAN. SULEMAN'S AUNT SAYS THE TEEN WAS TERRIFIED BUT WENT ALONG TO BOND WITH HIS FATHER. >> HE HAD A SENSE OF THIS WAS NOT -- THIS WAS NOT OKAY AND HE JUST -- HE WAS NOT VERY COMFORTABLE ABOUT DOING IT. >> Reporter: THE COAST GUARD SAYS THE U.S., CANADA, FRANCE AND BRITAIN WILL HAVE TO DETERMINE WHO WILL INVESTIGATE AND WHETHER TO RECOVER THE VICTIMS. SO CLOSE TO "TITANIC'S" FINAL RESTING PLACE WHERE 1,500 PEOPLE DIED IN 1912. STILL TO BE DETERMINED WHO PAYS FOR THE SEARCH AND POTENTIAL RECOVERY. THE COMPANY HAD BEEN DIVING TO THE "TITANIC" SINCE 2021 CHARGING CUSTOMERS AS MUCH AS A QUARTER MILLION DOLLARS FOR THE EXPERIENCE, BUT A FORMER EMPLOYEE AND OTHER SUBMERSIBLE EXPERTS HAVE LONG WARNED THE SUB WAS NOT CERTIFIED TO DIVE SO DEEP. IN 2018, THE CHAIRMAN OF A COMMITTEE OF 38 CONCERNED SUBMERSIBLE EXPERTS WROTE TO CEO RUSH ASKING HIM TO ADHERE TO OUR INDUSTRY ACCEPTED SAFETY GUIDELINES AND PROTOCOLS FOR ULTIMATE SUCCESS. IN 2021, DISCOVERY CHANNEL HOST JOSH GATES DECIDED AGAINST TAKING THE SUB DOWN TO THE "TITANIC" FOR HIS TV SHOW. >> I JUST FELT AS THOUGH THE SUB NEEDED MORE TIME AND NEEDED MORE TESTING, FRANKLY. >> Reporter: INVESTIGATORS DON'T YET KNOW WHY THE SUB IMPLODED. IT MIGHT HAVE SURRENDERED TO THE CRUSHING PRESSURE NEARLY 400 TIMES WHAT IT IS AT SEA LEVEL. PERHAPS A FATIGUE CRACK DEVELOPED IN THE TITANIUM CARBON FIBER SHELL AFTER SO MANY DEEP DIVES. >> IT'S HARD TO IMAGINE, IT'S ONE EMPIRE STATE BUILDING MADE OF LEAD SITTING ON TOP OF YOU AT THAT LEVEL. >> Reporter: IN A HAUNTINGLY CRUEL TWIST OF FATE, STOCKTON RUSH'S WIFE WENDY LOST RELATIVES IN THE "TITANIC" MORE THAN 100 YEARS AGO. NOW HER HUSBAND HAS LOST HIS LIFE IN THOSE SAME DEEP WATERS. >> TOM, WE ARE GETTING LATE WORD THE NAVY MAY HAVE ACTUALLY DETECTED THE SUB IMPLOSION DAYS AGO. WHAT MORE DO WE KNOW? >> Reporter: THAT'S RIGHT. THE NAVY TELLS NBC NEWS THAT AT ABOUT THE TIME THAT CONTACT WAS LOST WITH THAT SUB, ITS UNDERWATER DETECTION SYSTEM PICKED UP AKUSN
