But it doesn't have to be. Neil Johnson's sea kayaking trips off North Uist offer all this. And you do not need to be an expert paddler to join up. Sea kayaks are much the same as regular river kayaks, only longer, thinner and faster. They have enough room for provisions for a week's journey, and are strong enough to withstand quite high waves if the weather gets rough. Neil offers two basic types of sea kayak trip: for beginners, for which you should have some basic paddling skills, and for intermediate paddlers, which involves longer crossings between islands and is aimed at those who have skippered sea kayaks before.
If you have never held a paddle before, but like the sound of sea kayaking close to killer whales, spend a weekend at a local canoe club - easily found in the phone book or through your public library - to learn the basic strokes and get the feel of the kayak. Then make your booking with Neil.
Once up at Lochmaddy on North Uist, in addition to taking in the ocean, the mountain islands, long sandy beaches, wildlife, sea birds and the great empty silence while crossing the sounds, you will learn how to read tides, weather systems and currents, and the caprice of the open sea.
At whatever level, you are likely to encounter marine mammals of various kinds. It is common to come across porpoises and dolphins lying asleep at the surface, drifting so close you could touch them. Schools of minke whales (pronounced "minkey"), one of the smaller baleen whales, hunt for krill in the sea lochs. And then, of course, there are the killer whales. Neil never leads paddlers close to these powerful creatures deliberately: "If it happens, it happens," he says. "It's just that it happens quite a lot off the Hebrides. We can easily find ourselves 30 yards or so from a breaching killer whale - though that is a bit close for comfort when he splashes back into the water. We let the whales dictate the meeting, rather than the trip leader."
Is it safe, I ask? Neil smiles: "There are two types of killer whale, sedentary and migratory. Sedentary ones, who stay around the same territory all year, are generally thought to be pretty safe. The migratory bands are another story - a bit more piratical, if you like. However we don't approach them close enough to try to find out which is which. We stay out of their zone, and have never had an accident or bad incident with the pods around here."
And then there are the seals, not just the herds lying up on the rocks of Harris and North Uist, but the much larger colony of the Monach Isles, whose 30,000-strong population of grey seals is one of the largest in the world. The seals are always with you while you paddle, popping up to look at you with their curious, almost human heads.
As for where you sleep and eat: the beginner trips tend to be based from Neil's bunkhouse at Lochmaddy, though he will do his best to get clients onto the longer stretches - and camping out on the islands - as soon as possible. The intermediate trips spend all nights but the first and last under canvas. Food and equipment are included in the general tariffs.
Trips usually last a week, but weekend, long weekend, and even breaks as short as a half-day can be arranged.
Uist Outdoor Centre, Cearn Dusgaidh, Lochmaddy, Isle of North Uist, PA82 5AE, Scotland
Tel: 01876 500480.
May to September.
All food provided. Special diets by prior arrangement.
Prices include instruction, equipment and accommodation. One-week beginner trip: pounds 305 (full board). Weekend breaks: pounds 120 (full board) Day trips: pounds 50.
Neil's bunkhouse is basic but comfortable and has dormitory rooms. Once out in the islands you camp, usually on the beaches.
All trip leaders are qualified British Canoe Union (BCU) Level 3 Coaches, and are trained in sea rescue. A powerboat can be called in case of emergencies.
Over 15 years only.
10% non-refundable deposit required. Balance due 28 days before start date. Late bookings accepted if space available.
Drivers must take ferry from Kyle of Lochalsh to Uig (on Skye), then to North Uist. Trains are available to Kyle of Lochalsh, buses are available to Uig. Pickups from ferry terminal on Uist can be arranged by the centre. If you fly from London to Edinburgh in the morning, you can catch a connecting flight to Skye and then take the ferry to North Uist. Contact the centre for more details.