If you're reading this, it probably won't come as much of a surprise to you, but whales are not fish. They're mammals, and they need to breathe air, just like us.
Yeah...I know. It's something that should be obvious, but it's amazing how often otherwise well-educated people ask me about what it's like to swim with "such a big fish". I guess it's just a symptom of how little humanity collectively understands about the ocean. Sigh.
Anyway, here's a photograph of a very relaxed sperm whale coming up for a breath of fresh air after diving down to forage for food:
If you look carefully, you can just make out the whitish area around the jaw of another sperm whale behind this beautiful female. The pair came up together, chilled out for a bit, then headed back down to the deep blue.
If you ever come across a sperm whale or two at the surface, take some time to look around. These whales often synchronise their dives and surface intervals, so when you see one, there's a reasonable chance that are there more within visual range.