The most dangerous waters for merchant seamen

Where was the most frightening place for a civilian or merchant sailor to serve at sea during World War II?

The Arctic, because a sailor in the water had almost no chance of surviving long enough for rescue.

The North Atlantic was extremely dangerous, but larger convoys and nearby escorts could improve a survivor's chance of being recovered. Arctic water itself was effectively unsurvivable once a sailor went overboard. Mediterranean and some Pacific waters were warmer, giving survivors more time even when enemy action remained severe. Arctic service combined exposure to attack with particularly poor prospects after abandoning ship.