To the sound of the 007 theme tune, the secret agent swoops through the deep. The criminal mastermind bent on world domination thinks he’s safe in his watery lair, but he has reckoned without Bond and his latest piece of subterranean technical wizardry...

Hmm. Perhaps not. I’m going at one knot, and I probably wouldn’t win a Sean Connery lookalike competition. But let me have my fantasies. I’m riding a BOB, and they were made for make-believe.

A what? It takes some explaining. Cast your mind back to the first year of General Science at school. At some point, the teacher made you turn a cup upside down, push it underwater, and then pretend to be amazed when the air stayed in the cup. As I didn’t envisage a future career as a diving- bell designer, I didn’t pay attention at the time, but now it all comes flooding back (metaphorically speaking), because simple physics is the only thing between me and a watery grave.

The designers of this gizmo (the initials stand for Breathing Observation Bubble) took the simple displacement principle our teachers were so keen to get across, and adapted it slightly. They made the cup into a Perspex dome about 2ft across; piped in a constant supply of new air from an oxygen cylinder; added a little motor and steering mechanism; and put the whole lot together with a sit-upon fibreglass chassis. Result: I’m scooting about the deep with my head in an oversized cup. And loving it.

They sound Heath Robinson, they look James Bond, but — and here’s the beauty of it — you don’t have to be 007 to use one. It’s as easy as pie. The land-based instruction course lasts all of five minutes, and you don’t even have to be able to swim. Diving, the usual method of getting down with the fishes, requires a fair bit of commitment and aptitude, but here’s a way of doing it that’s both effortless and idiot-proof. Which sounded right up my sea-lane.

BOBs are a big thing at Stuart Cove, the largest dive outfit in the Bahamas. Now, the Bahamas, neatly enough, is a favourite James Bond location — it provided the backdrop for much of Thunderball, and they’ve just finished extensive underwater filming there for what will be Daniel Craig’s first outing as 007, Casino Royale. Where better to test a piece of kit that looks straight out of Q’s workshop?

THE BEST way to get onto a BOB is to wait in the water while it’s lowered down off the back of the dive boat: when it’s half submerged, slide onto the seat and allow the rest of it to be lowered over you, like a dryer hood at a hairdresser’s. And then you’re under, sinking towards the sand and reef.

It’s the most peculiar feeling. Here you are, looking up at the bottom of the boat, but at the same time the surface of your own personal bit of briny is a few inches below your chin. From the shoulders down, you’re certainly in the water — in early May it was just fresh enough to make a wetsuit an attractive option — but from the neck up, you’re dry and filling your lungs naturally with God’s good air.

You need to equalise the air pressure in your ears as you go down (just pinch your nose and blow) but that’s the only diver-style inconvenience there is. Just get to your desired depth, and off you zoom. Well, not zoom, exactly. That one knot is the top speed, and it’s about as fast as a lazy breast stroke. You’re not going to give Daniel Craig any sleepless nights.

No matter: we’re not here to race. Of the eight BOBers on this trip, none is a diver, but all want to sample the novelty of nosing around the reef and watching the sealife. The fish hang back for a moment — you would too, we look pretty peculiar — but, after a minute, curiosity overcomes them and shoals surge over the rocks to surround us. It’s the charge of the fish brigade.

Instantly, the water around my dome is a seething mass of life and colour. It’s probably nothing the average diver hasn’t seen dozens of times, but if, like me, you’ve never seen this sort of display without a David Attenborough voice-over, it’s breathtaking. On land, wild animals are shy and elusive. Down here, they come right up to you and gawp. So this is what those divers have been keeping to themselves all this time. No wonder they look smug.

I click the motor and pootle off. A blue parrotfish follows, 18in of doleful curiosity, her long, lugubrious face set in a comically disappointed frown. She escorts me around her home turf, shimmying over to pretty bits of coral and shells. It’s anthropomorphic, but I instantly christen her Polly, and God help me, I start talking to her.

I’m not the only one. There’s a lot to remark on down there, and with no respirator stuck in your mouth, the natural thing is to go ahead and remark on it. I looked round to see half a dozen of my fellow submariners happily babbling away to themselves and the fish as they BOBed about the deep. We look like a group of day-trippers from the Jules Verne Home for the Terminally Confused, but we don’t care: it’s fabulous down here. If only my science teacher had made displacement this entertaining, I might have paid more attention.

The details: Sunset Faraway Holidays (020 8774 7100, www.sunset.co.uk) has five nights in Nassau, room-only, at the water-themed Atlantis resort, from £905. Or try First Choice (0870 850 3999, www.firstchoice.co.uk).

Stuart Cove (00 1 242 362 4171, www.stuartcove.com) has half-day BOBs (called SUBs here) for £59. Other resorts with personal submersibles include Playa de las Americas, Tenerife (BOB Diving, 00 34 670 839516, www.bob-diving.com) and Cancun in Mexico (Cancun All Tours, 00 52 998 848 1060, www.cancunalltours.com).

Page 2: five more ways to go deep without diving

()Five more ways to go deep without diving

TAKE an undersea walk. You wear a head-sized helmet, supplied with air via a hose from the surface, and stroll the sea bed. Try Hartley’s in the Bahamas (00 1 242 393 8234, www.underseawalk.com), or Captain Nemo’s (00 230 263 7819) in Mauritius.

HOP on a tourist submarine. There are dozens worldwide: two of the most well established are the Atlantis XI in Grand Cayman (00 1 866 546 7820, www.atlantisadventures.com) and Submarine Safaris in Lanzarote (00 34 928 512898, www.submarinesafaris.com).

BOOK a table at an undersea restaurant. Ithaa, at the Maldives Hilton (www.hilton.co.uk), is housed in a glass tunnel 16ft below the Indian Ocean. Do try the chilli-pickled lobster. Don’t say “cod and chips twice”.

SLEEP with the fishes in an underwater hotel. Currently, your best bet is Sweden’s Utter Inn (book on 00 46 21 39 01 00), with one room 9ft below a lake in Vasteras; but full-scale, five-star sunken hotels are planned to open next year in Dubai and the Bahamas.

FEEL the energy flow at a sunken spa. At Huvafen Fushi (www.huvafenfushi.com) in the Maldives you can enjoy your fruit wraps as the wrasse float by the submerged picture windows.

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