Sergio Hanquet / Green turtle (Chelonia mydas) swimming in proximity to boat propeller; propellers are a danger to sea turtles. Tenerife, Canary Islands.

Shane Gross / Boat propeller scar runs through a Seagrass (Thalassia testudinum) meadow in The Bahamas. The prop scar is caused by a boat's propeller digging up the root structure of the underwater plant.

David Fleetham / Diver swimming behind the propeller of the wreck of the Hilma Hooker, a 236 foot long cargo vessel that sunk in 1984 off the island of Bonaire in the Caribbean.

Cyril Ruoso / Long-tailed Macaque (Macaca fascicularis) mother and young jumping off boat propeller, Khao Sam Roi Yot National Park, Thailand

Cyril Ruoso / Long-tailed Macaque (Macaca fascicularis) climbing up boat propeller, Khao Sam Roi Yot National Park, Thailand

Tony Wu / Southern right whale (Eubalaena australis) fluke marked by injuries that appear to be the result of a propellor strike from a boat traveling at high speed, photographed with the permission of the Depa...

Tony Wu / Humpback whale (Megaptera novangliaea) engaged in bubble net feeding, note the injury to dorsal fin possibly from boat propeller, Chatham Strait, Alaska, USA July, .

Pascal Kobeh / Whale shark (Rhincodon typus) swimming on top of a coral reef, with scars from an injury due to boat propeller, Maldives. Indian Ocean.

Roland Seitre / Humpback Whale (Megaptera novaeangliae) with boat propeller injury

Franco Banfi / Yellow sponges (Aplysina cavernicola) on propeller pt the wreck 'Vassilios T', Vis Island, Croatia, Adriatic Sea, Mediterranean

Franco Banfi / Scuba diver exploring Viana wreck, the hull is covered with spiral Tube-worm (Sabella spallanzani). Propeller of Viana wreck, a vessel set on fire in the Horta harbour. In attempt to contain the fire,...

Franco Banfi / Propeller of Viana wreck, a vessel set on fire in the Horta harbour. In attempt to contain the fire, the boat was sunk there. After a few months, the vessel was mended to float and transported to the...