The force required to lift a submerged object from the bottom can be split into two main components:

The Explorer sank within 20 hours after striking an unknown submerged object reported to be ice.

They are found subtidally, attached to slow-moving submerged objects or organisms.

The boat was cut short by the irreparable damage to the rudder after a collision with an unknown submerged object.

Normally, a boundary layer of still water surrounds a submerged object, which acts as a barrier.

It also reduces the risk of the propulsion system being seriously damaged by submerged objects.

Cuts from submerged objects and immersion in standing water had caused the swelling, as well as infection of both feet.

Hitting submerged objects is also a threat that is difficult to prevent but easy to insure against.

They may also be used to dredge for submerged objects.

Everyone's heard of UFOs, but what about unidentified submerged objects?