Marine mammal lovers in Metro Vancouver had yet another treat Thursday, when more than 150 Pacific white-sided dolphins frolicked in the waters near Horseshoe Bay.

Veteran whale researchers say they've never seen a pod this large so close to the city.

Marine biologist Lance Barrett-Lennard told CTV News that the dolphins could just be following their food -- herring.

"They're big eaters. A large group like this needs quite a lot of it to keep well fed. They're very food motivated, so that means there's something in here for them to eat, and I suspect it is herring," he said.

The dolphin display was just the latest in a series of rare sightings this week.

Yesterday and again this morning, a grey whale ventured into Vancouver's False Creek, delighting hundreds of eager whale watchers, and another grey whale was spotted near Squamish on the weekend.

Iain White of the Vancouver Aquarium said that it's very rare to see greys in this area.

"We get a lot of sightings of them in the inshore areas around Crescent Beach and Boundary Bay, but we certainly don't get to see them this close to home very often."

The aquarium's B.C. Cetacean Sightings Network maps whale and dolphin sightings throughout B.C. to assist with marine mammal conservation.

Anyone who spots a whale or dolphin anywhere in the province should call the sightings network at 1-866-I-SAW-ONE, or use a sightings form on the network's website .

With a report from CTV British Columbia's Mike Killeen