A submersible vessel carrying five people disappeared on Sunday on its way to the wreckage of the Titanic. The The U.S. Coast Guard is leading the search for the small craft in a remote area of the North Atlantic Ocean.

Experts warn that many obstacles remain: from pinpointing the vessel’s location, to reaching it with rescue equipment, to bringing it to the surface—assuming it’s still intact—before the passengers’ oxygen supply runs out.

Vice Adm. Robert Murrett (Ret.), professor of practice of public administration and international affairs, says the disappearance of the submersible underscores the dangers associated with operating in deep water and the recreational exploration of the sea and space, “two environments where in recent past we’ve seen people operate in hazardous, potentially lethal environments,” Murrett says.

“I think some people believe that because modern technology is so good, that you can do things like this and not have accidents, but that’s just not the case,” he says.

Read more in the Associated Press article, “The US Coast Guard is bringing in more ships, vessels to search for lost Titanic tourist submersible.”

Murrett was also quoted in the USA Today article, “For Coast Guard, search for tourist sub near Titanic is a rescue unlike most others.”