Two sei whales were spotted Monday just outside of Ma'alaea Bay by the captain and crew of the Pacific Whale Foundation's Ocean Quest whale-watch vessel.

They were returning in a skiff from mooring the boat when the whales appeared in approximately 50 feet of water.

Sei whales are baleen whales, like humpbacks, but are significantly longer. Their bodies are narrower than humpbacks and they have shorter flippers and a tall, sickle-shaped dorsal fin.

Sei whales can be found worldwide, but tend to stay primarily in deep, temperate waters. Sightings in Hawai'i are extremely rare, according to the foundation.