they cant
Not without breathing apparatus.
A SCUBA (self-contained underwater breathing apparatus) tank
The fishes have gills for breathing
Scuba - self contained underwater breathing apparatus
No. Only fish can. No other animals have gills or means of breathing underwater. Well, except those who have oxygen tanks that is. THEN you can breathe underwater.
In the word SCUBA the letter B stands for breathing.
a breathing tank! try it its fun! (underwater swimming)
Frogs can breathe underwater only for 20 minutes at a time. They breathe by using oxygen that is dissolved into the water and breathe through their skin.
Unless you have gills or a SCUBA (self contained underwater breathing apparatus), you will drown. *Edit* Also learn some grammar please.
you can't breathe underwater
The ability to breathe underwater in Oblivion can help you later on, but you don't necessarily NEED it. There is one quest, the quest that unlocks the master alteration trainer, in which you'll need to breathe underwater. However, at that point, you'll be at least an expert in alteration and will know the breathe underwater spell. Plus, you might not even decide to explore alteration.
An aqualung is a piece of equipment consisting of an oxygen tank and breathing apparatus used by divers to allow them to breathe underwater at depth.