I found this on the Minecraft Wiki page for Ocelots:
A cat will not teleport: [...]
- If none of the blocks on the edge of a 5×5×1 region centered on the player are transparent blocks with an opaque block below and another transparent block above.
Does this mean that if I tame a cat (which is not sitting), and boat across an ocean, the cat will be on the beach and not teleport near the water? If cats swim, will they drown after a while in the water, even if I use a lead?