Stuart Thompson, from the RNLI, says one of the risks of tombstoning is the sheer unpredictability of the environment.
"The problem is that you know heights of tides change, conditions change" he says.
"The conditions of the seabed change as well so it's actually quite a dangerous practice".
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Three Welsh billionaires have made this year's Sunday Times Rich List, with Sir Michael Moritz topping the list for the richest in Wales.
A fine end to the weekend, with sunny spells throughout the day. Moving into the start of the week, more bright spells but feeling colder.
Off to the London Marathon today? If so, send us in your pictures.