It would be hard for me to walk like that. One species, the ring seal, spends most the time under the ice. It's easier to keep pushing its nose in the holes so they won't have to make new holes. If their not looking out so if a polar bear sees its hole it won't catch it. Seals are great divers and can stay under water for a long time without even taking a breath of air.
Mature seals mate in the spring.
Calves are born in the spring, the next year. They stay with their mother for a few weeks until they know how to catch and prey. The soft baby fur is not warm enough for the baby. When the white fur turns darker, it is better suited to the arctic waters. There are a lot of seals in Antarctica.