The red-and-white squid was filmed by Diving Shop Kaiyu owner Akinobu Kimura.
"My curiosity was way bigger than fear, so I jumped into the water and go close to it," he told CNN.
He then swam with the animal as he helped guide it back to the deep ocean.
"This squid...looked lively, spurting ink and trying to entangle his tentacles around me," Kimura said.