Sailor Hat Explosion Crater

In October 2005 I was lucky enough to volunteer and visit Kahoolawe, a Hawaiian island used for bombing practice by the US Military since 1941. The bombing has stopped and the island is in the process of being rehabilitated. I volunteered with KIRC - the Kahoolawe Island Reserve Comission - to do some good "dirty" work preparing for the coming planting season. (In addition to the bombs, goats and cattle had done serious damage to the vegetation of the island)

Among other interesting things done to the island, in 1965, the Navy decided to investigate the effects of a large "conventional" explosion on their ships, twice (maybe 3 times). The US was no longer doing nuclear tests in the open air.

500 tons of explosive were piled up near the shore, and set off, with a few ships parked just off shore. A second blast was set off at the same location, leaving a nice crater. (I haven't found out if they filled in the crater in between)

A fuller description:

Fortunately, we had time to visit the crater in the morning, and the low sun was able to bring out what appeared to be shattercone in the rocks.

Military images first:

pile of explosives

Rockets were flown overhead to observe the shock effects - in addition, aircraft were also flying overhead and recording the tests.
Do a search for Sailor Hat on YouTube, and you'll find the moving images.


The shock wave is easily visible.


Not only is the initial shockwave (on the water) visible - but also compression/rarefaction waves setting off condensation clouds.

boom and shockwave

Military images not displayed - Pile of Explosives - Explosion - Explosion

Movie of one of the Explosions

After the two tests, this is an aerial image of the crater. Date uncertain - but much after the tests and before my visit in 2005.


From Google Earth - the appearance of the crater currently (within the last few years)

SH google earth

Crater Rim size is between ~76 and ~86 meters (measured with Ruler in Google Earth)

size      size

Approaching the crater from the "car park"

Panoramas of Sailor Hat Crater - 500 Tons of TNT makes a nice hole in the ground - 75-86M

pan 2

Water was extracted from the crater for awhile - see the pipe above. It's brackish.


Piece of Basalt with melt effects


Outer rim of the crater - ejecta and melted basalt

A series of what appears to be shocked basalt / shattercones




shock effects


Pictures - short description

Fuller description - similar images

Images by ted Brattstrom-2005, Google, USNavy
Page updated 15-Apr-2009