I just spent a few days last week photographing the elephant seals at Ano Neuvo State Park in California. While this is a fun photographic opportunity to photograph the Elephant seals as the come back to this state beach every winter. These seals can be engaged in bloody battles for territory and mating rights. This is also the time of year the females come ashore to deliver and ween their pups. So you can see it all during this short window of time. There are few things to look for, before you plan your trip - the most important - you have to have a ticket.
Be sure to get tickets to go on the tour well in advance. The prime months to see the seals are January and February (thats when all the seal activity happens) and tours book up rather fast. You can buy tickets (about $7 for adults) for a tour up to about 60 days in advance. Remember, you can't see the seals without being on a tour at this time of the year, so plan ahead.
When you are choosing a tour time slot, definitely go as early as you can in the morning. The light is much better on the seals early in the morning and since there are so many limitations as to where you can stop and shoot photographs on on your tour - the morning is the only way to go. These animals are highly protected at this time of year so you will moved in small groups by docents and rangers and you will only get to spend limited time with the seals.
While I hiked with a 600mm lens and a specialized tripod, you may want to bring gear that weighs a lot less. The hike to see the seals is about two miles and part of it is in sand dunes, so lightweight gear might be what you want to bring. On the flip side, since the seals are protected, you wont be allowed to get very close for both your safety and for the safety of the seals. That means you may want to bring the longest lens you have. So you have to make a decision on the weight of your equipment vs. how close you want to photograph your subjects.
The seals should only be part of your trip to Ano Neuvo State beach. Since the tour only lasts a couple of hours you will have plenty of time to photograph other wildlife in the area as well as scenic coastal landscapes. Ano Neuvo is a 25 minute drive down from Half Moon Bay along highway 1 so there are all kinds of views to stop for.