My character Cody (me) can turn aquatic thanks to his magical necklace.
While in this form, Cody can swim faster & farther underwater by propelling with his flipper-like paws that he has sprouted (along with with his fins & hand webbing), he can also glide with his armpit webbing.
His shark-like ears also enables him to hear things from outside the water, he can also also see clearly underwater.
His head fins, however, adapts to the temperature of the water from icy cold of the lakes to pleasantly cool and very light (just like the effects of gillyweed from Goblet Of Fire).
And lastly, Cody can both breathe & survive underwater thanks to his gills that come out both on his neck and the sides of his chest, it also allows him to talk underwater though the downside is that bubbles come out of his mouth in the process.
(Unfortunately, his aquatic form doesn't have the ability to talk to feral marine/aquatic creatures like dolphins or regular fish).
To turn aquatic, Cody must clutch his necklace. To turn back to normal, Cody needs to clutch his necklace again.
Anyways, here's a picture of what Cody looks like in his aquatic form.
