Everyone knows that Killary Harbour is Ireland's only fjord, but how many are aware that Lough Hyne in west Cork is the only inland sea lake in Europe?

A geographical freak, and the site of Ireland's first marine research station, Lough Hyne offers worrying evidence of the effects of global warming. At low tide, its emerging river flows noisily into the sea. But as the tide rises, its water surface falls below sea level, and the river switches direction.

Like all the best walks, this route offers a variety of scenery, from wooded glades to Lough Hyne's shoreline and the sheltered coast at Barloge Creek nearby. To get to the start, take a clearly signposted left turn four kilometres west of Skibereen on the Baltimore road. Lough Hyne (or Ine) is another four kilometres down the road. Park at a small layby beside the entrance to Knockomagh Wood.

Start off right up through the forest, following the signs for the "hill top". At first, it's all mundane conifers, but as you ascend the tree type changes. Knockomagh is an ancient wood populated by oak and beech trees for thousands of years. There has been some planting of trees in more recent times, but the intrinsic beauty of the forest remains.

Look out, too, for evergreen yews, the orange leaves of the spindle tree and the forest's rich undergrowth, including ivy, wood sorrel, ferns and pennywort.

From the top, retrace your steps to the bottom and head for the road that passes along the west side of the lake.

When we last passed this way in July, the roadside was ablaze with flowers, most of which I could not name, and butterflies dancing in the breeze. There's also a ruined castle, all smothered in ivy, on an island in the lake.

Follow this road with the lake to your left until the next junction and turn left down to Barloge Pier. Well sheltered from the ocean, this is a popular spot for passing yachts to take a breather. You're also likely to see local fishermen bringing ashore their ocean bounty in the form of live lobsters and crabs. It's a good place for a picnic or even a swim.

From the pier, retrace your steps to the junction.

Head right back to where you started or straight on up over the hill for views of Roaringwater Bay and Baltimore. Following this road right in a circle will bring you back to the start.

For more information see Kevin Corcoran's West Cork Walks