If you are feeling comfortably warm blooded you can go look for seals across most cold water coastlines, but if you want to see lots of them go to the arctic (while it still exists).
There are 5 types of seals (harbor, ring, ribbon, spotted and bearded). They combine to hunter and prey in themselves. They keep marine life in balance with their diet and act as diner for others (polar bears, orca's etc)