Why did people on boats and out diving survive the Tsunami?

Question

On the Tsunami programme on the BBC the people who went scuba diving were not affected by the Tsunami - why?

Answer 1

The tsunami wave is a few meters high but may be many miles long and moving very fast so each lull in the wave sucks the water out of the bays and such - then when the crest arrives it is a few meters high but the miles long wave keeps rolling in and the volume of water piles up and rushes in devastating any thing in its path due to the volume of water and the breaking on shore causing it to pile-up. If you are out at sea in a boat you just go up a few meters as the crest hits and then down a few meters as the lull hits.

Answer 2

At the point where the ocean floor breaks or is disturbed by an earthquake, waves roll quickly towards the coast. Because the ocean floor is deep further out, the waves are still smaller and less threatening. When the depth of the floor decreases as it approaches the shore, the water then has no more room to roll which is what creates the tall wave or wall of water. By the time the Tsunami hits, the ocean is now calm and poses no threats to anyone still out to sea.

Answer 3

A tsunami does more damage in shallow water, close to shore.

If you're away from shore in a boat or diving, you have a lot of deep water for the wave to move through, and it wont do much. But at the shore, all that water gets pushed up and has to go somewhere, so it goes onto land and does lots of damage.

Answer 4

Due to the nature of wave formation, waves far from the coast are actually just bulges in the water, and it would have to be a huge wave to capsize a boat out from shore. As the wave gets closer to land, it increases in height and speed and decreases in width and stability, and so it collapses.