My two sons and I have clambered up a rock face on the right of this pretty bay in our wetsuits and helmets. After wading through a cave we reach a deserted sandy beach backed by high grassy cliffs. This, experiencing the inaccessible, is a big part of the appeal of coasteering — working your way along a coastal route by any means necessary.

However, my sons, and the other children in our party, seem to get more out of the route’s pièce de résistance — the daunting rhino jump, a plunge into the sea from a rock shaped like a rhino’s head.

Sounds like an extreme adventure in New Zealand, doesn’t it? Actually, we were coasteering in Jersey in the Channel Islands, a place that is better known for offshore banking than for extreme sports. My sons, Harry, 14, and Elliot, 11, showed little interest in Jersey’s history as we sped there on a ferry. Instead their thoughts were summed up by Harry: “What is there to do?”

I had a few aces up my sleeve. We were staying at the Merton Hotel in the capital, St Helier, and were taking our sons to the UK’s first FlowRider. “Flowboarding” blends surfing, wakeboarding and snowboarding. A jet of water is pumped up a sloping, cushioned surface to create a wave, which can be ridden either in a prone position on a bodyboard or standing up on a custom-made flowboard.

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Jamie De La Haye, one of the hotel’s instructors, took charge of a group of would-be flowboarders on our first morning. Soon he had his party of boys and girls — and the more adventurous parents — gliding up and down the FlowRider on foam bodyboards.

Coming from a surfing background, Harry, Elliot and I found the prone position easy enough, but how would we fare when we tried to stand up? De La Haye made it look easy, carving his flowboard around as if he were off-piste on a snowboard. I had a feeling that we might take a while to reach the same level, and so it proved. Harry and I managed to turn from side to side, but Elliot opted for the swimming pool.

All this had given us a need for the real thing — stand-up surfing. In St Ouens on the western side of the island, Jersey has a beach with good waves and a surfing history as rich as any in Britain. St Ouens was the scene of the first British surfing championships in 1965 and has hosted several European championships. We arrived to find well-formed waves breaking on the five-mile expanse of sand. Harry declared that he would be happy to surf for the rest of our stay, but the following day the swell disappeared.

Determined not to be defeated by this minor setback, we opted for the coasteering. Cliffs are a prerequisite, so too competence as a swimmer, as Penny Setubal, chief instructor with Jersey Pure Adventure, confirmed. But Setubal said that coasteering was not an extreme sport — and children as young as 8 could take part.

Jersey isn’t all watersports. One of the island’s popular land-based activities is blokarting, a cross between go-karting and sailing. The three-wheeled kart is directed with a steering wheel while a sheet rope, attached to the sail, controls the speed. Within a few minutes we were flying around a circuit on Ouaisne beach, wheels sliding on every turn.

Blokarting was genteel compared with what was on offer at Creepy Valley Activity Centre. Deep in a secluded valley near Jersey airport, we found the optimistically named “aerial trekking course”. In my case, despite being clipped on to steel wires with a harness, it was “aerial terror”. I made heavy weather of traversing a series of beams, ropes and obstacles.

After five days on Jersey it was all I could do to climb the steep steps of Mount Orgueil, a castle above the picturesque village of Gorey. But from its ramparts, gazing over the Royal Bay of Grouville and with the coast of Normandy shimmering in the distance, my wife, Karen, and I watched as a swimmer eased himself into the sea below. Joining him was irresistible. Once in the water, we could dimly hear the boys on the nearby rocks. Only the FlowRider would do for them.

Blokarting

Coasteering

Jersey Surfboard Club

Need to know

Getting there

The Condor Express from Poole (condorferries.co.uk ).

Where to stay

The Merton Hotel (01534 724231, www.seymourhotels.com ) has rooms from £51.50 until December 12.

What to do

FlowRider costs £2.50pp for an hour’s group session. Creepy Valley Activity Centre (01534 638888, www.creepyvalley.je )

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