Lough Hyne

Lough Hyne was a freshwater lake until rising sea levels breached the ridge around four thousand years ago, and it became fully marine. Its only connection to the sea is the Rapids, a channel a few metres wide where water pours in for about four hours as the tide rises and out for eight as it falls, running fast enough to be audible. That restricted exchange, combined with unusual depth - over forty metres in one basin - and the mild water, produces a marine community found nowhere else in Ireland: over seventy fish species and around eighteen hundred marine species recorded, including Mediterranean animals at the northern edge of their range. It became Europe's first marine nature reserve in 1981 and has been studied continuously by University College Cork since the 1930s. Swimming is popular but the reserve status means care matters; the Rapids current is strong and boats are restricted.

What you actually see

• The Rapids - the narrow channel that reverses direction with the tide.
• The marine life - around eighteen hundred species, some at their range limit.
• The depth - over forty metres in the main basin.
• The reserve status - Europe's first, designated in 1981.

When to go

May to September for the water temperature. The Rapids are most dramatic at mid-tide. The hill walk above the lake gives the overview and takes about an hour.

Honest expectations

A protected reserve - taking anything, including shells and animals, is prohibited. The current through the Rapids is strong and unsafe to swim against. Parking is very limited and the access road is narrow.

Nearby

Skibbereen is inland; Baltimore and the West Cork islands are south.