Pitch Lake is forty hectares of natural asphalt at La Brea on the southwest coast of Trinidad, in Trinidad and Tobago, the largest deposit of its kind in the world, 76 metres deep at its centre, firm enough to walk on and still quarried at 180 tonnes a day, and it closes its own scars overnight, so that the pits dug in it by day are level again by morning. The lake sits over a fault where oil from deep below seeps up and loses its lighter parts, leaving the tar, which slowly circulates like a very thick pot, so that tree trunks and tools that sank into it centuries ago work their way back to the surface; the crust takes the shape of a foot the way cool wax would, holding every toe, and the guide's line runs across the plates of hard pitch, threading between the pools, to the centre the locals call the Mother of the Lake, where the surface looks wrinkled and freshly poured and gives softly underfoot. Walter Raleigh caulked his ships with it in 1595 and noted that it does not melt in the sun, and the pitch paved the streets of London and New York.
Rain collects in the folds of the tar into pools that run warm, clear and faintly sulphurous, with gas seeping up through them in strings of small bubbles, and the locals wade in to sit and ease aching joints, so a visit ends with a soak in a sulphur pool on top of a lake of asphalt. The tar is not sterile, since microbes were found living in it in 2011 in droplets of ancient seawater. The Chaima people, the story goes, feasted on the hummingbirds that carried the souls of their ancestors, and the gods swallowed their village in tar for it. At the southern edge the diggers cut the pitch for export, and the dry season leaves the paths firm. Pitch Lake is a lake that is walked across, and it heals every hole made in it.