Tooth-in-the-Sea is an Argonian who is a Master Alteration trainer. He wears a mage's robe and hood, and carries a small amount of gold. He can be found north of Bravil, east of Flooded Mine in Niben Bay.
During the night, he can be found by his camp. He gets up at six in the morning and he spends twelve hours swimming around in the vicinity of his camp.
Before he agrees to train the Hero, they'll have to spend three hours with him underwater. They must speak to him and begin the task before 1pm, else he will say that "It is too late in the day to begin your test" and will ask them to return the next day.
In real time, the test will only take about 5–6 minutes. There are three options to complete this quest:
- Be an Argonian, and therefore have the inherent water breathing ability.
- Keep casting a water breathing spell and repeat as many times is necessary to complete the test.
- Wear a piece of equipment with Water Breathing. The Jewel of the Rumare, obtained from the side quest Go Fish, is a good choice since it is easy to get. Alternately, wear a Fin Gleam during the test. Or, simply make a Water Breathing Ring at an altar of enchanting, and wield it while underwater.
In any of the cases, they'll have to remain very close to Tooth-in-the-Sea, or they won't be able to rise to the surface to breathe.
After completing this mission, they'll be able to train Alteration skill up to Master Level. However, like all trainers, he will only offer his services while he is awake, and can therefore be somewhat difficult to find after completing his task, and the quest marker has gone.