The first and most seaward gap is about 20 meters wide and the 2nd the most fantastic; gap is about 10 meters wide. When the rising or falling tide occurs, the water builds up in front of the gaps faster than it can flow through them. This in turn make an astonishing waterfall effect as the water rushes through and then down to the lower levels on the other side of the ridgelines. The course of action is reversed and it is repeated again in the opposite direction. The tides in this vicinity have a 10 meter variation which occurs over 6 1/2 hours from low tide to high tide and vice versa. On a slack tide it is likely to drive boats through the two gaps to the bay behind. The gorgeous waterfall phenomena has been described by David Attenborough as "one of the greatest natural wonders of the world".