The Pembrokeshire Islands: Skomer, Ramsey, Caldey and the Rest

Five islands off this coast are worth a day, and they are not interchangeable. Pick the wrong one for what you want to see and you'll have spent forty pounds looking at the wrong birds.

Skomer — the famous one

The one people mean. Skomer holds one of the world's largest colonies of Manx shearwaters — several hundred thousand pairs — and, more visibly, thousands of puffins that nest in burrows right beside the footpaths.

Puffins are ashore from roughly April to late July. Miss that window and the island is still lovely, but the puffins have gone back out to sea.

The thing to understand about Skomer is landing permits. Numbers ashore are capped, boats are weather-dependent, and permits are released online in advance and go extremely quickly — think concert tickets, not a day out. Book the moment they release, and have a second date in mind, because the crossing from Martin's Haven is cancelled often.

In late April and May the island is carpeted in bluebells, which is the other reason to go.

Skokholm — the quiet one

Skomer's smaller neighbour, and much harder to reach. Skokholm is mostly a research and ringing station, with limited overnight stays rather than day trips. Britain's first bird observatory was established here in 1933. If you're serious about birds and can plan months out, it's the better island. If you want an afternoon, it isn't an option.

Ramsey — the one off St Davids

Reached from St Justinian's, a couple of miles from St Davids. RSPB-managed, high cliffs, choughs, peregrines, and one of the biggest grey seal pupping colonies in southern Britain — from late August through autumn the coves fill with pups.

The crossing goes through Ramsey Sound, which contains the Bitches, a reef that generates one of the fiercest tidal races in Britain. Some operators run dedicated jet-boat trips through it. It is genuinely spectacular and not a place for a private boat unless you know exactly what you're doing.

Grassholm — the gannet rock

Eleven miles out, a bare rock that turns white in summer: one of the largest northern gannet colonies in the North Atlantic, tens of thousands of pairs. You cannot land — it's RSPB-owned and closed — so trips circle it. On a calm day the smell arrives before the island does.

Caldey — the monastery

Different in kind. Caldey lies just off Tenby and has been home to monks on and off since the sixth century; a Cistercian community lives there now. Boats run from Tenby harbour, frequently, in season only, and usually not on Sundays.

You get a village, a chapel, a lighthouse, beaches and a perfume made by the monks from island wildflowers. It's the easiest island day here by a distance, and the right one with children or anyone who doesn't want a rough crossing.

Practical, for all of them

Weather cancels crossings more often than visitors expect, even in July. Build slack into the week rather than pinning the trip to your last day.

Book direct with the boat operators — they publish their own schedules and know the sea state. Prices, seasons and permit rules change every year, so check the operator's own page rather than anything written here.

Take everything you need. Facilities on the islands are minimal to non-existent, and there is nowhere to buy lunch.

See boat trips and activity providers, or find places to stay near Martin's Haven and St Davids.