The Weddell seal pup shouldn’t be alive. Antarctica, after all, is Earth’s freezer—a place where exposed skin freezes in minutes and the ocean hovers just above the solidification point of saltwater. Yet here’s this blubbery infant, sprawled across volcanic rock that’s radiating heat like a planetary heating pad, looking about as comfortable as a cat in a sunbeam.
When Underwater Mountains Decide to Become Radiators for Marine Mammals
Deception Island is one of those places that sounds made up. It’s an active volcano in the South Shetland Islands, and its collapsed caldera forms a natural harbor that occasionally—without warning—decides to remind everyone it’s still very much awake. The last eruption was in 1970, but the heat persists. Geothermal vents bubble through the seafloor, warming the frigid Antarctic waters to temperatures that would make a penguin do a double-take.
Seals figured this out long before scientists did.
Researchers from the British Antarctic Survey documented Weddell seals hauling out on these thermally active beaches starting in the early 2000s, particularly around Whalers Bay. The seals weren’t just passing through—they were deliberately choosing these spots for pupping and molting, behaviors that demand energy reserves most Antarctic seals simply don’t have to spare. One study from 2018 recorded surface temperatures on these volcanic beaches reaching 25°C (77°F), which in Antarctica is basically the tropics.
The Metabolic Math That Makes Hot Rocks Worth the Trip
Here’s the thing: maintaining body temperature in Antarctica is exhaustingly expensive. A seal pup can burn through 40% of its energy budget just staying warm. But on volcanicaly heated substrates, that cost plummets. The pups essentially outsource their thermoregulation to the Earth’s mantle, freeing up calories for growth instead of just not freezing to death.
It’s not just Deception Island, either. Turns out seals have been exploiting volcanic warmth across multiple locations. On Bouvetøya—a Norwegian volcanic island so remote it makes Deception look like downtown—researchers observed similar behavior among Antarctic fur seals in 2015. The seals congregated around geothermal zones during molting season, when they lose the insulating properties of their fur and become vulnerably exposed to the cold.
Wait—maybe this isn’t just opportunism.
Some biologists now suspect this behavior might be ancient, possibly dating back milenia to when seal ancestors first colonized polar regions. Volcanic activity was more widespread then, and these thermal refuges could have been critical stepping stones in their evolutionary adaptation to extreme cold. It’s speculative, sure, but the behavior appears too sophisticated to be accidental discovery by modern seals.
The Unexpected Consequences of Living on a Geological Time Bomb
Of course, there’s a catch. Volcanic systems are magnificently unreliable. The 1967 eruption at Deception Island destroyed a scientific research station and forced a complete evacuation. Any seal unlucky enough to be hauled out during an eruption would face a choice between scalding or swimming—neither particularly appealing.
Yet the seals keep coming back. Population surveys from 2019 showed increasing numbers of Weddell seals using Deception’s geothermal sites, suggesting the benefits outweigh the existential risks. Which raises a fascinating question about animal risk assessment: do seals understand probability, or do they just really, really like warm rocks?
Climate Change Is Rewriting the Thermal Playbook Entirely Now
As Antarctic temperatures creep upward—the peninsula has warmed nearly 3°C since 1950—the energetic advantage of volcanic beaches may be diminishing. Seals that once depended on these thermal hotspots might find the ambient environment tolerable enough to abandon the volcanic lottery altogether. Or maybe not. Behavioral ecology rarely follows predictable scripts.
What’s clear is that seals possess an almost unsettling ability to identify and exploit microclimates most humans would never notice. These animals are basically thermal prospectors, mapping geothermal gradients across some of the harshest terrain on Earth, all to shave a few percentage points off their metabolic overhead.
And they’re doing it without GPS, geological surveys, or any of the tools we’d consider essential. Just whiskers, instinct, and an apparent willingness to nap on what is, technically speaking, an active volcano.
