Ancient Mariners and Giant Squids?

The Giant Squid has mostly remained a mystery, although recently a few have been observed alive. From what I understand, Sperm whales hunt them, and giant squid being very large itself, fights back leaving scaring on the whale from it's suckers. These encounters always seem to take place in very deep water, yet ancient mariners, have accurately described seeing the Giant Squid, on the surface. Is this is possible? Could surface actions with Sperm Whales, and attacks on ships be possible?