Even though it’s high summer in the Antarctic, the ocean around the Rothera research station is -1 Celsius. As some of the most productive oceans on the planet – a soup of microscopic plant and animal plankton – it’s murky to boot. Not everyone’s idea of the perfect scuba spot. But the divers I’m with seem positively excited about tipping themselves backwards into the depths. Image: A seal swims by icebergs off the British Antarctic Survey’s Rothera base. File pic: Reuters “You can get these big starfish with 40 arms that you don’t see anywhere else, they’re my favourites,” said Pati Glaz, a marine biologist with the dive team of the British Antarctic Survey (BAS). For her dive partner, BAS marine biologist Matt Bell, it’s “polar gigantism” that floats his boat. No, me neither. It’s the phenomenon, he patiently explains through a thick neoprene helmet, of species exclusive to cold polar oceans growing much larger than their cousins in warmer waters. The colder the water, the more oxygen it can carry, and the more animal …