The entire population of grey whales (over 20,000) swim past the west coast twice a year, traveling between summer feeding in the Bering and Chukchi Seas and their nursery and breeding grounds in California, and Baja Mexico. Grey whales are medium-sized, up to 45 feet long. Their dark, slate grey skin is covered with white patches caused by barnacles and parasites. They have no dorsal or back fin. Sighted along the entire West Coast.