Where did the Titanic sink? The wreck location may not be where you think it is.

• Five people in a submersible heading for the RMS Titanic shipwreck have gone missing.
• The Titanic was found in 1985 and is about 400 miles off the coast of Newfoundland.

A submersible named Titan heading for the shipwreck of the RMS Titanic has been missing since Sunday, leading to an intense search operation led by the US Coast Guard, US Navy, the Canadian Coast Guard, and the Canadian military's air & marine search and rescue team.

The five passengers who lost communications with the Canadian research ship The Polar Prince include the CEO of OceansGate — the company in charge of the exploration — three British nationals, and a French diver.

The Coast Guard estimates the sub will run out of breathable air by Wednesday evening.

OceansGate estimates the largest piece of wreck, which is split into two main pieces, exists at a depth of 2 ½ miles — or 12,800 feet — about 400 miles off the coast of Newfoundland in the North Atlantic Ocean.

The Titanic, described as "unsinkable" before its first and final voyage from Southern England to New York City, sank on April 15, 1912, after hitting an iceberg.

In 1985, explorer Robert Ballard found the Titanic after requesting the US Navy help fund the technology needed to reach the shipwreck. The US Navy agreed, but only if Ballard helped them with the USS Thresher and USS Scorpion — two sunken submarines that ended in disasters. The Navy wanted to investigate how the disasters happened.

Ballard convinced the Navy, and then-President Ronald Reagan, to let him search for the Titanic — which was estimated to be somewhere between the two submarine wrecks — while on his mission. His rationale was that if the Titanic was found by the US Navy, it would demonstrate their might and "drive the Soviets crazy," according to Ballard in the 2021 book "Into The Deep." Reagan agreed with the idea, he wrote.

Then, at the end of August 1985, a team led by Ballard came across the shipwreck in their submarine. Ballard described it as "a quiet and peaceful and fitting place for the remains of this greatest of sea tragedies to rest."