A submarine carrying tourists has been lost in the North Atlantic while diving to see the ruins of the RMS Titanic ship. A search and rescue effort has been dispatched Monday morning according to the Boston coastguard. 

A  spokesperson confirmed to The Guardian that  “a small submarine with five persons onboard had gone missing in the vicinity of the Titanic wreck”. 

Read more: New Titanic scans show wreck as never seen before

OceanGate Expeditions operates the submersible, which explores the wreck, which is located on the ocean floor at 12,500 feet of water about 370 miles off the coast of Newfoundland.

The Titanic is the most notorious maritime tragedy that claimed the lives of 1,514 people on a voyage from Britain to the United States in 1912.

Our thoughts and prayers go out to those on the missing sub. We pray they are safely returned to the surface and are thinking of their friends and families. #oceangate pic.twitter.com/6OQMdsjGVn

— TitanicBookClub (@TitanicBookClub) June 19, 2023

OceanGate began transporting small crews of "citizen scientists" in a five-person mini-sub for $125,000 per person two years ago. The cost of a trip is now estimated to be $250,000.

Oceangate had scheduled an eight-day, seven-night excursion to the disaster for June 12-20, according to the company's website. Six tourists had planned to leave and return to St John's, Newfoundland, Canada.

Hamish Harding, 58, a British businessman, aviator, and adventurer is believed to be on board the sub. 

On his social media accounts, Harding announced the trip. On Instagram, he wrote:I am proud to finally announce that I joined @oceangateexped for their RMS TITANIC Mission as a mission specialist on the sub going down to the Titanic.”

On Saturday he posted that the mission is "likely to be the first and only manned mission to the Titanic in 2023. A weather window has just opened up and we are going to attempt a dive tomorrow. We started steaming from St Johns, Newfoundland, Canada, yesterday and are planning to start dive operations around 4 am tomorrow morning. Until then we have a lot of preparations and briefings to do.”

On Monday, Oceangate announced its website that extensive assistance has been offered from "several government agencies and deep sea companies in our efforts to re-establish contact with the submersible."

Stockton Rush, the founder of Oceangate told The Guardian earlier this year that "We spend 1,000 times as much exploring space as we do exploring the ocean in the US,” adding that “How the ocean responds to climate change is going to dictate everything. We need to understand it.”

Rush explained that nearly half of the customers are "Titanic obsessives," and others are merely deep-sea enthusiasts.