The DePalm tour in Aruba costs less and has a special underwater walkway for cruises traveling through a sunken Cessna plane. That sounds even better, as does Dolphin Trek at Xel-Ha Park in Riviera Maya. You can also find Sea Trek in the Bahamas (at Atlantis Resort), Belize, Honduras, Puerto Rico, Grand Cayman, St. Lucia, St Maarten, US Virgin Islands and – soon – Jamaica, at Dolphin Cove. In Mexico, Xcaret park and other suppliers in Cozumel also offer Sea Trek.

If you really don’t want to bother with any equipment but still want to see what diving under the surface is all about, check out Atlantis Adventures. This company, operating in Aruba, Barbados, Cayman Islands, Curacao, Cozumel and St. Martin, provides a once-in-a-lifetime opportunity to get down to real submarines and see corals, marine life and wrecks.

It’s a noisy, no annoying experience: You line up at the dock, a small tender boat takes you out to the side anchors, and a fixed gangplank allows you to easily access a hatch and Stairs lead to the cottage. (Climbing the stairs can be difficult if you have a physical problem, and the side cannot be disabled.) When inside, place your position on the opposite two rows of seats facing a row of large glass windows.

It was cozy but not crowded even with 40-plus passengers on board, and when my daughter and I went to sub Atlantis in Aruba, we never felt like our outside view was obscured. In fact, the views are great, the cabin is air-conditioned, and there’s really little sense of motion in this battery-powered, quiet accessory – a good thing if you’re prone to motion sickness.

The sub dives about 130 feet and offers close-ups looking at a large coral formation and a sunken ship; a handy fish identification guide helps you figure out what’s swimming by the window, and a digital display shows you how deep you are. The experience is well worth the $ 100 or so splurge – after all, how many chances would you have to come down in an extra, Jules Verne style?