Still being rather dazed from your sudden change to underwater breathing, you can't see clearly yet but your limbs feels all soft and limp. Perhaps some sort of paralysis effect? Surprisingly, you can still move them all as usual, it's just that they feel a lot more bendable now. Frankly, they're so movable you hope you didn't break anything somehow. Your vision is starting to clear up and as you look at your legs you see...rows of suction cups?
You check your arms, but the result is the same. In total, eight large tentacles have formed on your body, with an empty spot in the center of them. You feel your head, and luckily it hasn't changed (yet) though your skin has changed to a color pattern more appropriate for an octopus. You push yourself through the water with the entirely natural feeling motions of your tentacles, rippling in a wave pattern with each push.
You come to the surface for a moment, and much to your surprise it's no problem for you to breathe as normal; your respiratory system must be amphibian. You try to go on land for a moment, but this is not quite as easy: you don't manage to get far before your squishy and boneless tentacles become too tired to carry the rest of your body. Besides, you are feeling rather dry out here so you decide to slip back into the water.
Now it's time to consider your next move. Sure, you could spent the rest of your life swimming all day and eating raw fish, but what fun is that?