- A thick layer of blubber: Blubber helps seals stay warm in cold water, but it also helps them to filter out salt from seawater.
- Kidneys that are able to concentrate urine: Seals' kidneys are able to remove excess salt from their bodies through urine. This helps them stay hydrated even when they are drinking saltwater.
- A mouth and throat that are lined with mucus: The mucus helps to protect the seals' mouths and throats from the salty water.
Seals also drink freshwater when it is available.