Dolphin and porpoise are passing marine visitors, grey seals are resident and can often be seen bobbing about in the surf and hauled out on the outer reefs. Annual summer visitors such as sunfish can be spotted.
The Skerries Bank is a large stretch of mobile sand and is host to flat fish including sole, plaice, various species of ray and large shoals of sand eels which live in the coarse sand and gravel that drops away steeply in dramatic waved dunes. Many crabs also find a home here.
There are also rocky reefs around Start Point with chimney sponges, scarce finger sponge and dahlia anemones.