Divers were stunned when their routine trip turned into a rare wildlife spectacle as they witnessed two massive fin whales breaching alongside dolphins and hundreds of bluefin tuna off the Devon coast.

The extraordinary encounter was captured on drone footage last week by University of Plymouth student Alistair Walsingham, 22, and unfolded about 35 miles south of Plymouth in calm, clear waters.

Fin whales are rarely seen in the English Channel, making the sighting of two together - amid tuna and dolphins - an exceptional moment for local marine experts.

Divers and crew from In Deep Dive Centre were aboard the dive boat Size Matters searching for a possible shipwreck when they witnessed one of the rarest sights in the Channel.

Two enormous fin whales travelled alongside a pod of dolphins, while hundreds of tuna churned the waters beneath them.

As the divers wrapped up their excursion, the crew spotted a massive bait ball of tuna near the surface.

Alistair, who was crewing the trip, said: "We slowed down to watch it, and then off our starboard side one of the whales fully breached - just completely out of the water.

"It was massive and none of us realised at first that it was a fin whale."

Fin whales - the second-largest animal species on the planet after the blue whale - are exceedingly uncommon in the English Channel.

Sightings have been so scarce that Alistair says he doesn't personally know anyone who has ever reported one in the region.

"Seeing one would be unbelievable enough, but there were two of them together, and with dolphins riding their wake," he said.

Alistair, a student of oceanography and coastal processes, launched his drone as the commotion intensified.

Within moments, he captured 4k aerial footage of the whales gliding through the Channel with dolphins darting around them.

Below them, hundreds of tuna flickered just beneath the surface, moving along their migratory route from Portugal.

"To see dolphins, tuna, and fin whales all in the same area - it's just not something you expect, especially here," Alistair said.

"It was one of those moments when everyone on board was jumping around with excitement."

The return of bluefin tuna to the Channel in recent years is already considered a significant ecological shift.

Once absent from these waters, the species has begun reappearing thanks to recovering populations of forage fish like herring and sardines.

For marine observers, the simultaneous presence of tuna, dolphins, and fin whales suggests the Channel may be becoming a far more productive ecosystem than in decades past.

"I don't know the exact reason the whales were there, but it probably relates to the tuna," Alistair said.

"I've been told that fin whales will come in after feeding events like bait balls, possibly taking advantage of the leftover particulate matter.

"I can't say for sure, but just the fact that animals this big are feeding here shows how rich the habitat is right now."

For Alistair - who hopes one day to run his own dive boat and continue marine photography - the experience was as thrilling as it was humbling.

He had only recently purchased his drone to document the growing number of bait balls in the Channel, but never imagined he would capture one of the rarest wildlife encounters in British waters.

"The scale of these animals is just unbelievable," he said.

"To be there in the middle of the Channel, watching two fin whales breach while dolphins played around them and tuna surged below - it was unforgettable."