Forget napkin folding and deck quoits. These days, you should expect the unexpected when you set sail. Here’s my pick of seven of the strangest things you can do on a cruise ship:
1. Walk the plank
Harness up and don’t look down as you walk a plank just six inches wide that juts over the side of Norwegian Cruise Line’s Norwegian Escape, 160 feet above the water.
That isn’t scary enough for Royal Caribbean International, so they have put a plank over the side of Icon of the Seas, 154 feet above the ocean, that falls away, leaving thrill-seekers to zipline back to base. Only those with a head for heights should try it.
2. Dive, dive, dive in a submersible
Channel your inner David Attenborough on a diver beneath the waves in a seven-man submersible on Scenic Ocean Cruises’ discovery yachts, Scenic Eclipse I and Scenic Eclipse II. He dived at the Great Barrie Reef, but you don’t have to go to Australia to follow in his footsteps as weather permitting, Scenic Neptune goes exploring the depths of the ocean in the Caribbean, Mediterranean and even beneath the frozen waters of the Arctic and Antarctica.
Not to be outdone, Seabourn has put two subs on each of its expedition ships, Seabourn Venture and Seabourn Pursuit that come with a Champagne chiller.
3. Get spellbound
See that nondescript black door on Princess Cruises’ new Sun Princess? It might not look very interesting but step inside (you need to buy a ticket first) and prepare to be wowed by magicians with hands that move faster than the eye can see. There’s a Victorian-themed bar, a theatre and plenty of close-up sleight-of-hand tricks that promise to amaze.
4. Become a scientist
Don’t panic! This is not a back-to-school moment with lessons about electrons and molecules (they went straight over my head as well!) Rather, it’s hands-on Citizen Science at sea projects courtesy of HX.
There are Science Centers on all its ships with high-tech gadgets and touch screens to play with, and passengers are encouraged to learn more about the environments they are visiting by analysing water samples, counting penguins, recording bird, whale and dolphin sightings, observing cloud formations and more. If only science at school had been such fun.
5. Tie the knot
This is nothing to do with weddings, although you can get hitched on several cruise ships. Rather, it’s all about learning about nautical knot-tying with the crew on Star Clippers’ sailing ships.
If that doesn’t appeal, then how about harnessing up and climbing the mast? This is another for those with a head for heights as you have to be able to shin up a ladder as far as the main top (about 20 metres high), but it’s worth it for the terrific views across the ocean.
6. Underwater mission
“Not another submarine,” I hear you say! Well, yes. But this time you’ll be on the fictional Arvia II and have to turn detective with your sub-mates (up to 10 at a time) in order to solve puzzles and problems and avoid danger as you sail into ocean canyons, visit sunken cities and encounter marine critters.
It’s all very realistic in 3D surroundings. In case the sub’s name didn’t give it away, the adventure is on P&O Cruises’ Arvia.
7. Peek behind the scenes
Ever wondered what goes on behind those doors on cruise ships marked ‘Crew Only’? Hop on one of Cunard’s Queens and all will be revealed on a Behind the Scenes tour.
It lasts about three hours and takes passengers up and down stairs in the beating heart of the ships, visiting the galleys and bridge, the backstage area in the theatre, the medical centre, the engine control room and more. Wear flat closed-toe shoes and expect a lot of walking. 
