Hydrotherapy (8a+) takes a steep line to the right of the still unrepeated trad route Underworld (E7) that was established by Ben Bransby and Ian Vickers.

Liam Cook accompanied Neil on his attempts and captured the ascent on video. Here he introduces his film:

"Filmed in the summer of 2011 this film follows Neil Gresham, one of the UK's most prominent all round professional rock climbers, as he embarks on one of the most challenging routes of his career, 'Hydrotherapy'.

'Hydrotherapy' takes the line of greatest steepness through the soaring, Gothic architecture of Hollow Caves Bay in Pembroke, Wales. Climbing rope-less with only the sea to catch him, Neil could only safely attempt the route during a high, spring tide when the water would sufficiently cover the jagged reefs below. Discovering that the cave would remain wet until an hour before sunset meant that this tide had to rise precisely at the right time. When the sun was low enough in the sky, the face would be bathed in an incredible golden light and the moisture, burnt away.

So, the seas had to be calm, the weather, mild, and he had to have someone on hand to fish him out in case of emergency. Even getting to the base of the route presented problems which required an unusual and creative approach. As if to add insult to injury, the cliff falls within a restricted area of land, controlled by the military. Several attempts were thwarted by the unpredictable closure of this land, exacerbating a sense of frustration, made keener by the wasted 500mile return trips from London.

So when the illusive window of opportunity finally creaked ajar, Neil had to be ready to climb something at his physical limit. The resulting experience surely had to be one of the most cathartic and memorable of his life.

It has been my pleasure to try and capture it.

Thank you,

Liam Cook "

VIDEO: Hydrotherapy