It appeared to be a 5-7m Cuvier's Beaked Whale, part of a family of beaked whales that dive to at least 300m to hunt squid. This one had scars caused by bites from "cookie-cutter" sharks, but these marks were common and unlikely to have caused fatal injuries.
Cuvier's beaked whales are wellknown from strandings around NZ and are found in most of the world's oceans. But the chances of actually seeing any of the 11 beaked whale species known to inhabit our waters is slight - in some cases, they're only known to exist due to their bodies washing up.
It's unclear if this particular whale had stranded or had died and was then washed up on the beach: an autopsy will hopefully confirm the cause of death.
This is not the first whale to die on Titahi Bay. In the 1950s, a large sperm whale washed up in the area.