At 2nd level, a wizard gains the Arcane Tradition feature. Here is a playtest options for that feature: Hydromancy.

School of Hydromancy

You are a student of spells that manipulate one of the four elements, water. To you, water is a near infinitely mutable form of matter. From frozen mountain peaks, to steaming pipes, to ancient carved rivers. Your magic allows you to manipulate this element into whatever form you desire.

Few mages take up the study of hydromancy, but those who do are able to powerfully affect the world around them. Some hydromancers are paragons and saviors, able to provide fresh water for lost travelers or brings fields of crops back from the brink of death. Others are renegades and plague bearers, threatening towns with disastrous floods, or sinking ships and looting their treasure.

Water Ward 2nd-level Hydromancy feature Starting at 2nd level, you are able to manifest a swirling vortex of water around your body, manipulating it to defend yourself from harm. You can use a bonus action to activate your Water Ward, which lasts for 1 minute. It ends early if you are incapacitated, if you wear medium or heavy armor, or don a shield. You can also dismiss the water at any time you choose (no action required). While your Water Ward is active, you gain the following benefits: You gain a bonus to your AC and Dexterity saving throws equal to your Intelligence modifier (minimum of +1).

You are considered to be fully immersed in water, and have resistance to fire damage. You can use this feature twice. You regain all expended uses of it when you finish a short or long rest.

Aquatic Adaptation 2nd-level Hydromancy feature Beginning when you select this school at 2nd level, your latent magic allows you to glide through water as effortlessly as you would walk across land. You gain a swim speed equal to your walking speed. Additionally, you learn the shape water cantrip if you don't already know it.

Aquatic Acclimatization 6th-level Hydromancy feature At 6th level, your defensive ward grows in power to absorb some of the damage inflicted upon you. When you activate your Water Ward, and at the start of each of your turns while it is active, you gain temporary hit points equal to your Intelligence modifier (minimum of 1). You also have become acclimatized to the chilling effects of water. You gain resistance to cold damage. Furthermore, you add the water breathing spell to your spellbook, if it is not there already. You can cast water breathing once without expending a spell slot. When you do so, you can target only yourself.

Aquatic Restoration 10th-level Hydromancy feature At 10th-level you have learned how to call on the restorative powers of water. You add the lesster restoration spell to your spellbook, and it is a wizard spell for you. You always have it prepared, and it doesn't count against the number of spells you can prepare. You are also able to wash away an ailment affecting a creature. As an action you can cleanse a creature you touch of a debilitating effect. You can reduce the target's exhaustion level by one, or end one of the following effects on the target: One effect that petrified the target

Any reduction to one of the target's ability scores

One effect reducing the target's hit point maximum Once you do so, you can't use this feature again until you finish a long rest.