In my experience, sea creatures are markedly more agressive than land creatures. Explorers on land during my games have mostly been left alone by aliens except when two hexes or so from an alien nest. Even the dreaded, earth drinking siege worm does not automatically attack (but I do not put anything adjacent to one if I can possibly avoid it!). This actually makes sense, as IRL sea predators are much more agressive than land dwellers. They have to be, as you can escape a lot faster in an ocean environment (three dimensions, and no obstacles except at the bottom or top of the sea).
Now carriers... I never thought of using trhem for scouting as they seemed too high value. See, my experience is that early game, gunboats on auto explore WILL be eaten, and until the observatory quest and unles you build the Panopticon, manually exploring is too time consuming and ultimately risky. Does having an embarked tacjet increase the visual range of a carrier? I know they did in Civ V, but I've only used carriers late game, and with heavy escort... That would be interesting! My only alternative so far has been to get the aliens friendly, by buying a tile on top of an alien nest. When blue, even the kraken is peaceful. Just bobbing around like a big adorable murder death kille mountain at sea...