Notice What the Tide Reveals

In the North Atlantic, kelps such as Laminaria form dense underwater forests that shelter fish, crabs and juvenile animals and dampen wave energy. In the Pacific, giant kelp can grow tens of metres tall. Snorkellers should avoid trampling holdfasts in the shallows and never cut fronds.

Seagrasses are flowering plants that store carbon and nurse young fish. In the Mediterranean, Posidonia oceanica meadows are protected and very slow to recover from anchor damage. If you charter a boat, ask the skipper to anchor on sand or use moorings.

Maerl is a slow-growing, unattached red seaweed that builds pinkish gravel beds, sometimes taken for coral fragments on beaches. Living beds grow only millimetres a year and are easily damaged by dredging and anchoring. Leave maerl on the beach.

Atlantic puffins return to burrows on islands such as Mykines in the Faroes, Fair Isle and Skomer from roughly April to August. Gannets pack cliffs and stacks; St Kilda's Boreray holds one of the largest colonies in the world. Stay on paths, keep low and still, and back away if birds become agitated or fly off nests.

Around Britain, grey seals pup mainly in autumn, common seals in summer. Mothers may leave pups alone on beaches for hours. Keep well back, keep dogs leashed, and never move a pup. Report concerns to a local marine rescue group instead.

Choose operators who follow recognised codes such as the UK WiSe scheme: approach slowly, never chase, and let animals choose whether to come closer. From land, calm days and high vantage points give the best sightings.