In addition to the cold, the emperor penguin encounters another stressful condition on deep dives—markedly increased pressure of up to 40 times that of the surface, which in most other terrestrial organisms would cause barotrauma. The bones of the penguin are solid rather than air-filled which eliminates the risk of mechanical barotrauma. While diving, the emperor penguin's oxygen use is markedly reduced, as its heart rate is reduced to as low as 15–20 beats per minute and non-essential organs are shut down, thus facilitating longer dives. Its haemoglobin and myoglobin are able to bind and transport oxygen at low blood concentrations; this allows the bird to function with very low oxygen levels that would otherwise result in loss of consciousness. You’re also naturally adapted to cold climates, as described in chapter 5 of the Dungeon Master’s Guide.

is the tallest and heaviest of all living penguin species. The male and female are similar in plumage and size, reaching 122 cm (48 in) in length and weighing from 22 to 45 kg (49 to 99 lb). Feathers of the head and back are black and sharply delineated from the white belly, pale-yellow breast and bright-yellow ear patches. Like all penguins it is flightless, with a streamlined body, and wings stiffened and flattened into flippers for a marine habitat.

The emperor penguinfolk gets a bonus +2 to constitution and +2 to charisma

While diving, the emperor penguin's oxygen use is markedly reduced, as its heart rate is reduced to as low as 15–20 beats per minute and non-essential organs are shut down, thus facilitating longer dives. you can hold your breath for an hour.

You gain proficiency in survival and stealth.

You can speak, read, and write Common, Aarakocra, and Aquan.

you can walk 25ft and swim 60ft