Grímsey is surrounded by the North Atlantic Oceanwhich is cold arctic water. It is possible to take a swim in the ocean; it is clean - but cold, about 8°C during summer and 4°C during winter.
One has to be cautious of strong currents and waves around the coast and note that this activity is undertaken on your own responsibility.
Best areas to take a dip are on the west coast e.g. by the harbour.
Sea swimming visitors to Grímsey have al sorts of goals, some collect oceans, other like to swim across the Arctic Circle and other just simply enjoy swimming in pure and refreshing arctic waters.