Lough Hyne is a sea lake about 5 kilometres east of Baltimore and the same distance south-west of Skibbereen. It's almost completely enclosed by land, joined to the sea only by a narrow channel, so the tides rush in and out through a set of rapids. In 1981 it became Ireland's first marine nature reserve.
It's a quiet, lovely place. Time your visit for a change of tide and watch the water race through the rapids.