"The SS President Coolidge was a luxury liner that was built by the Americans and launched in 1931.
"I believe it was one of the most opulent cruise liners on the water back then; it had lounges and swimming pools and things that we see on all of today's ships but were very luxurious back then.
"After the attack on Pearl Harbour during World War II, it was turned into a troop carrier and in 1942 hit a mine while trying to enter the Espiritu Santo harbour.
"The captain ran it aground and the story goes that he ordered the troops to leave everything behind and go ashore, with the idea they would go back once it stabilised.
"Unfortunately, the ship listed onto its side and slid down the channel into the sea.
"I had a wonderful experience diving the wreck of the ship.
"The visibility wasn't brilliant that day but it was still a fabulous experience; there was great coral and lots of sea creatures, including a resident moray eel that pokes its head out.
"The wartime troops really had dropped what they had and left, so you can see things like cooking and eating utensils, pots and pans and everyday items still on the ship.
"My dive buddy had an underwater camera and he took a photo of me wearing a World War II helmet and holding a gun.
"Everything is encrusted with sea life but is otherwise exactly as it was left 70 years ago.
"I was having a lot of fun on the dive but when I came back to the surface, it gave me a chance to think about what those troops went through in the wartime situation, knowing their lives could end at any moment.
"They say you need to do about 10 dives to do the Coolidge properly, because it's so massive. I didn't have that luxury, unfortunately, but it was still a wonderful dive.
"I'm a keen diver - I used to do it for a living - and this was definitely a highlight of my diving experience."
Value for money
Dave's diving excursion, which he booked through P&O, took about 2½ hours and cost $119.
"That's excellent value compared to what you would pay here in Australia," he says.
"It included transport to and from the site [the Coolidge wreck is accessible from the shore] and all of our dive gear, including a wetsuit.
"To dive what is arguably one of the best wreck dives in the world, it's an outstanding price."
WHO Dave Ryan, of Green Point on the NSW central coast, travelling on his fifth cruise (and his fourth with P&O).
WHAT Diving the wreck of the SS President Coolidge, Vanuatu.
WHERE The SS President Coolidge wreck sits just off the shore of Espiritu Santo, the largest of the Vanuatu islands.
THE SHIP Dave cruised with his wife Sarah and young children Emily, 5, and Mitchell, 3, on P&O's Pacific Jewel (pocruises.com.au). They cruised for 12 nights from Sydney and back, visiting Vanuatu and New Caledonia.
As told to Jane E. Fraser
Have you done an interesting shore excursion? Drop us a line at email@example.com.