The Piedras Blancas rookery is one of California's great free wildlife stops. Boardwalks above the beach let you watch northern elephant seals at close range without disturbing them: huge bulls, nursing mothers, weaned pups, moulting juveniles, or dozing heaps of blubber, depending on the month.
There is no single bad season, but the mood changes. Winter brings breeding and pups; spring and summer bring moulting; autumn is quieter but still worth a stop. Stay on the viewing side of the fence and give the animals the distance they deserve.