U.S., N.Z. tested tsunami bombs

In 1944.

“The tests were carried out in waters around New Caledonia and Auckland during the Second World War and showed that the weapon was feasible and a series of 10 large offshore blasts could potentially create a 33-foot tsunami capable of inundating a small city.

“The top secret operation, code-named "Project Seal", tested the doomsday device as a possible rival to the nuclear bomb. About 3,700 bombs were exploded during the tests, first in New Caledonia and later at Whangaparaoa Peninsula, near Auckland.”

http://www.telegraph.co.uk/news/worldnews/australiaandthepacific/newzealand/9774217/Tsunami-bomb-tested-off-New-Zealand-coast.html

(“Doomsday device?” Maybe so, if your town was tsunamied.)

Also at gatesofvienna.