Blue whale (balaenoptera musculus). A blue whale tail. Gulf of California.

Blue whale (balaenoptera musculus). A blue whale tail and tail stock. Gulf of California.

Blue whale (balaenoptera musculus). A blue whale tail in the afternoon light. Gulf of California.

Blue whale (balaenoptera musculus). The tail of a blue whale can be up to 20ft across. Gulf of California.

Blue Whale (Balaenoptera musculus) fluke-up dive in the offshore waters of Santa Monica Bay, California, USA.

Blue Whale (Balaenoptera musculus) fluke-up dive at sunset in the offshore waters of Santa Monica Bay, California, USA.

Blue Whale (Balaenoptera musculus) fluke-up dive at sunset in the offshore waters of Santa Monica Bay, California, USA.

Blue whale (Balaenoptera musculus) surfacing with long back and characteristically small dorsal visible. West of Iceland.

Two Blue whales, (Balaenoptera musculus), diving together, Monterey Bay, California, USA

Blue whale, (Balaenoptera musculus), fluking up sequence 2/3, Monterey Bay, California, USA

Blue Whale (Balaenoptera musculus) Adult fluke-up dive - note the damage to the right fluke. Gulf of California (Sea of Cortez), Mexico.

Dwarf Sperm Whale (Kogia simus) Adult on the surface (dorsal fin detail) near Isla San Esteban in the Gulf of California (Sea of Cortez), Mexico. (rr)

Adult Sperm Whale (Physeter macrocephalus) dorsal fin detail note: crenulated edge. Upper Gulf of California (Sea of Cortez), Mexico.

A diving blue whale (Balaenoptera musculus) tail and dorsal fin. Gulf of California (rr)