Divers explore the wreck of the SS President Coolidge

Photo: Vanuatu Tourism Office

Imagine dropping down through crystal blue water, the only sound is your breath moving in and out as you glide past schools of fluorescent fish and cities of coral.

And then the ocean floor drops away and below in the gloom a 22,000 tonne ocean liner appears.

The SS President Coolidge sunk during WWII when it hit one of its own mines. Once an ocean liner, the gargantuan ship was transformed into a US troop carrier and sunk in 1942 after botched communications lead it astray.

Today the Coolidge is the world's largest, most intact and accessible WWII wreck and offers a once-in-a-lifetime experience for divers, although it would border on the terrifying for novices.

The wreck can be reached by boat as it lays only a few kilometres offshore from Luganville on Vanuatu's largest island, Espiritu Santo. Water visibility varies from 15-25 metres, offering a clear view of the wreck.

Divers are encouraged to spend a few days exploring its exterior before penetrating inside to see famous sites such as 'The Lady'.