Many species of whales and dolphins can be vulnerable to collisions with vessels.

Most reports of collisions involve large whales but collisions with smaller species also occur.  Especially with large vessels, collisions often either go unnoticed or unreported, particularly for the smaller species.

Not only can the animals be injured or killed; for some incidents there has also been damage to the vessel.  Serious or even fatal injuries to passengers have occurred involving hydrofoil ferries, whalewatching vessels and recreational craft.