WOODS HOLE, Mass. (AP) — A troubling documentary about the fate of the world's coral reefs is opening this weekend's Woods Hole Film Festival.

The acclaimed film "Chasing Coral" follows a team of divers, photographers and scientists trying to discover why coral reefs are vanishing at an unprecedented rate.

It's among more than 130 films — 52 narrative and documentary features and 81 narrative, documentary and animated shorts — being screened starting Saturday. The 26th annual festival runs through Aug. 5.

More than 100 filmmakers and other special guests are expected to attend the festival. NASA astronaut Sunita Williams, whose parents live in Falmouth, Massachusetts, is scheduled to answer questions following a Sunday afternoon screening of the documentary "The Mars Generation," about the quest for a manned mission to the red planet.