Underwater sculptures installed on the banks of Thames in London

The four horses and their riders, created by Jason deCaires Taylor, will only be revealed twice a day at low tide

At high tide, you might barely know they're there. But as the water level of the Thames comes and goes twice a day, with the tide, the four ghostly heads - and the horses they sit atop - slowly emerge fully into view.

The sculpture, entitled The Rising Tide, have been installed near the bankside of Vauxhall bridge and are the work of Jason deCaires Taylor, 41, an artist best known for creating the world's first underwater museum in Cancun, then again in the Bahamas.