Farne Islands

Boats leave Seahouses on the tide, since the harbour dries at low water, and are among the skerries in twenty minutes or so. Two dives is the norm, with the surface interval spent under the cliffs while terns and, into July, puffins work the water around the boat. Operators mostly run small hard boats and RIBs and drop divers straight into the gullies. The outer rocks carry real tide and are dived near slack, so departure times move from day to day and skippers rearrange the plan when swell builds.

The islands are the seaward end of the Great Whin Sill, and the quartz-dolerite that makes the cliffs carries on underwater as blocky, straight-sided gullies and columnar faces. Kelp covers the tops; below it the rock is upholstered in dead man's fingers and anemones. Inner sites are sheltered and forgiving, while the outer reefs sit in more water movement and hold plating, boilers and framing from ships that struck them, the same rocks that took the Forfarshire in 1838 and sent Grace Darling out from the Longstone light.

How you behave decides how the seals behave. Chasing one ends the encounter; settling on the bottom, staying low and letting the animal make the first move is what produces the long sessions people come back for, which usually begin with a shape over your shoulder that declines to leave. Depths run to about 20 m, so gas is rarely the limiting factor and cold tends to end the dive instead. It rewards photographers, and it works as an introduction to British boat diving for anyone already settled in a drysuit.