An award-winning American photographer and climate change activist died while snorkeling at the Great Barrier Reef on Monday.

Gary Braasch, 70, was on the northern end of the reef attempting to document the impact of climate change when he was found by another snorkeler “floating face down in the water,” the Australian Museum said in a statement. CPR and advanced resuscitation attempts failed, the museum said.

Queensland Police are investigating.

Braasch, from Portland, had been published by the New York Times Magazine, Life, Time, National Geographic and Smithsonian magazine, among others, according to his website.