Why It's Worth Knowing What You're Looking At

Few things make a passage memorable like a porpoise surfacing off the bow, or the bark of a seal hauled out on a rock you would otherwise have sailed past without noticing. The Welsh coast is one of the better places in Britain for this: Cardigan Bay's bottlenose dolphins, the grey seal colonies around Ramsey and the Skerries, the seabird cities of Skomer and Bardsey. Learning to tell a guillemot from a razorbill at 150 metres, or a porpoise from a dolphin, turns a long beat into something you are actively watching rather than enduring. It also helps you make far better decisions about how close to get.

Seals: Tying Down Which Species You're Seeing

Two species turn up around Wales, and one is far more common than most people assume.

• Grey seal — the big one. Adults run to two metres plus, with a distinctive Roman-nosed profile, a long straight snout and nostrils set well apart and parallel to each other. These are the animals on most Welsh haul-out sites, particularly around Pembrokeshire and the Llŷn.
• Common (harbour) seal — noticeably smaller, with a rounded head and nostrils that meet in a V. Fewer in number, and more often found in estuaries and sheltered inlets.

Watch the water too. Seals often surface with very little splash, head up, looking at you, then sink again. A grey seal pup is white-coated in autumn; common seals pup in early summer and their pups moult that white coat almost immediately in the water. If you find a pup alone on a beach, it is almost certainly not abandoned — keep well away and let it be.

Porpoises, Dolphins and Making Sense of a Dorsal Fin

Harbour porpoises are the most frequently seen cetacean in Welsh waters and the easiest to misread. Look for a small, low, triangular dorsal fin with a slightly rounded tip, and a slow rolling surfacing — the back comes up, the fin rolls through, then they are gone. They rarely breach and almost never bow-ride. A puff of spray may show where they have breathed: the old harbour name "puffing pig" is a good reminder.

Common dolphins are longer, with a taller, more curved fin and a distinctive hourglass pattern of cream and grey along the flank. They often travel in pods and will happily bow-ride. Bottlenose dolphins, the Cardigan Bay residents, are much larger and darker, with a heavy, hooked fin.

Seabirds You'll Actually Encounter

• Guillemots — brown-black and upright on ledges, with a dark head and a thin, pointed bill.
• Razorbills — similar in shape, but with a thicker, blunt bill crossed by a white line.
• Puffins — obvious in summer with that parti-coloured bill, though they spend most of their time at sea or underground in burrows.
• Gannets — large and white with black wingtips, folding into a plunge dive from height.
• Cormorants and shags — low in the water, often standing with wings spread. Shags fly with a hunched, neck-forward look and are smaller and greener than cormorants.
• Kittiwakes — small gulls with black legs, announcing "kitti-wake" from the cliff faces.

If you are near a colony between March and July, treat every cliff and stack as a nursery. One abrupt change of course under a nesting ledge can empty it for an hour.

Practical Seamanship Around Wildlife

Distance is the whole game, and the numbers are straightforward.

• Stay at least 100 metres from seals hauled out on rocks and from rafting birds. At pupping time, give them considerably more.
• Keep 300 to 400 metres from cetaceans as a starting point, and never position the boat between a mother and a calf or across their line of travel.
• Approach obliquely, never head-on or from directly behind. Slow to a steady speed under 6 knots and keep propeller noise low.
• Limit it to 15 minutes with any single group, and don't let the number of boats build up. Three vessels is plenty.
• If dolphins choose to bow-ride, hold your course and speed. Don't steer towards them, don't gun the engine to "play", and never chase.
• Keep binoculars to hand in a dry bag, and keep the engine well maintained — a suddenly loud exhaust or a failing impeller is often what scatters a pod.

Logging What You See

A sighting written down is worth far more than one you half-remember over a pint. Local marine records centres and national sightings schemes rely almost entirely on volunteer effort, and skippers are a large part of it.

Jot down the date, the time, your position from the chartplotter or a rough latitude and longitude, the species if you are sure, and the sea state. Count the animals, note adults against juveniles, and record what they were doing: travelling, feeding, milling or resting. Add anything useful about behaviour — a porpoise working a tide race, dolphins associating with a trawler — and a photograph if you have one. Estimate the distance at the time rather than guessing it later.

Don't worry about getting the species right. "Two probable porpoises, off Bardsey, southbound, in the tide race" is a useful record; a confident wrong identification is not. Send it in at the end of the trip while it is fresh, and you will have contributed something genuinely useful to a long-running picture of what lives along the coast you sail.