One of the pioneers of the Ice Bucket Challenge, a fund-raising phenomenon that has gone viral online, has drowned in an accident in the US, police say.

Corey Griffin, 27, had just attended an event to raise awareness and money for the motor neuron disease ALS when he was involved in a diving accident in Nantucket, Massachusetts, last week.

Police spokesman Carlos Moreira said Mr Griffin jumped from the roof of a two-storey wharf building into Nantucket Harbour about 2am on Saturday, August 16.

Mr Moreira said Mr Griffin was submerged, then floated to the surface. He then sank and did not come up again.