The Rosh HaNikra Grottoes are sea caves in a headland of white chalk on the Lebanese border of Israel, where the cliff drops seventy metres into the Mediterranean and the storms have hollowed it into some 200 metres of chambers that are walked through on a lit path, reached by a cable car that tips off the cliff top at a pitch of sixty degrees. The chalk is soft, and the winter waves have cut it into tunnels and rooms that the sea still enters, so that the walkway threads from chamber to chamber over bridges and along ledges with the water surging in below, turquoise where the light comes through the openings; stepping back into the unlit part of a chamber turns the mouth into a bright blue window, and with the winter storms gone the sea settles, stops churning the chalk and clears to the bottom through the warm months. The cable car covers the seventy metres to sea level in about two minutes, hanging over open water for most of it.
The headland was a crossing before it was a sight: Alexander's army is said to have cut a passage through it, and British engineers bored a railway tunnel through the cliff in 1941 and 1942 so that trains could run from Haifa to Beirut and Tripoli, and the tunnel is walked to a sealed door at the border. The armistice line between Israel and Lebanon was signed in the customs house here in 1949, and the fence, the naval base and the UN post are all in view from the clifftop. Three small islands about 800 metres offshore have been closed to people since 1965 so that seabirds can nest, and a Mediterranean monk seal, one of the rarest seals on Earth, turned up in the empty grottoes when the site was closed by war. Rosh HaNikra is a cliff the sea has entered, and the border runs through it.