A 60-year-old US Navy submersible that carried out the first survey of the tragic liner Titanic yesterday took the waters off St George.

The boat completed its first round of tests after a major refit designed to boost its performance.

The mini-submarine – called Alvin – made its maiden voyage after its upgrade off Penno’s Wharf in St George.

Ken Kostel, of the Woods Hole Oceanographic Institution, which operates the submarine, said that the team was pleased to be able to test Alvin’s abilities.

He added: “The folks who operate the sub – the pilots, the engineers – they’re all the people who also work on it every day, so they’ve seen it through this process.

“We have new people on the team for whom this is their first trip with Alvin, so they’re excited now to begin to run the system that they helped build.

“This launch is the essence of what the job is.”

Alvin, which carries a crew of three, was used by ocean explorer Robert Ballard in 1986 for the first survey of the ‘unsinkable’ RMS Titanic, which went down on its maiden voyage between Britain and New York in 1912 after it hit an iceberg.

Haunting footage shot by Alvin after the ship was located in 1985 was used in the smash hit 1997 movie Titanic, which starred Leonardo DiCaprio and Kate Winslet.

The vessel is owned by the US Navy and was built in 1964 as a research vessel for Wood’s Hole.

The boat can dive to a depth of about four miles – 6,500 metres – and is used to study underwater geology and marine microbiology.

Alvin is the US Navy’s deepest-diving research submersible and has completed 5,066 missions – more than all other US Navy submersibles combined.

Mr Kostel said that Alvin went through a complete overhaul in 2011 so it was strong enough to reach new depths.

He explained: “The sub comes in for maintenance every five years where they take it completely apart and put it back together.

“In 2011, during that maintenance period they replaced about 75 per cent of the sub’s systems that needed to be improved to handle the greater pressure.

“Last year when it came back for another regular maintenance period we finished that process and now it’s entirely ready for 6,500 metres.”

Mr Kostel said that Alvin, which was transported to the island on a US Navy ship, had visited Bermuda several times and had been lent to the Bermuda Institute of Ocean Sciences.

He added that the submarine would be tested in the open ocean today or tomorrow to check how it handled deep dives.

Mr Kostel said: “We’ll start shallow for the sub – 500 metres – and then proceed deeper and deeper every day until we reach its new maximum depth of 6,500 metres.

“Then the Navy will sign off on certification and say ‘okay, the sub is ready’.”

The submarine’s testing will be completed in Puerto Rico, where scientists will also use the boat to conduct research.