500
It attacks ships & whales but i don't think it attacks humans!
Either by way of the Suez Canal of the Straits of Gibraltar
through the straights of Gibraltar into the Mediterranean and then through the Suez canal
Some attacks were mistaken identity. Some attacks were because the ships were sailing in an Allied Convoy. Some attacks were because the ships were armed and Germany considered them as auxiliary warships. Some attacks were because the British were beleived to be flying neutral flags on their ships to trick the U-Boats. Some attacks were because the neutral was in Allied waters and the U-Boat Captain felt the ship was trading with the allies.
The general term is a pirate.
they threw you overboard.
Throw ropes with hooks attached to ships or even castles to scale the walls or sides of the ships.
A person who attacks and robs ships is typically referred to as a "pirate." Pirates often operate in maritime areas, seeking to steal goods and valuables from vessels on the open sea.
. . . submarine attacks upon merchant ships .
U-Boat
A pirate most probably. Or possibly a buccaneer.