Written about the bombing of Bikini Atoll, post-WWII, this is The Vaccines' answer to Dead Kennedy's "Holiday In Cambodia." "It's a song about the bombing of Bikini Atoll disguised as a song about summer," frontman Justin Young told NME.
The Bikini Atoll is a coral reef in the Marshall Islands, which lie in the Pacific Ocean. Between 1946 and 1958, 23 nuclear devices were detonated by the US military at seven sites located there. This song appears to reference the 1988 documentary of the same name, which examined the affects of the tests on the atoll's original inhabitants and the American soldiers who participated in them.
Here's a bonus fun fact: When Louis Reard created the bikini in 1946, he named it such as he predicted the garment would be as explosive as the atomic bomb that had been tested four days earlier on the Bikini Atoll.