This is an attempt for a Paladin Oath for Nesirie, Goddess of grief, the oceans and exploration (Birthright setting). Please critique, as I'm unsure of the power of the capstone feature and the spell list.

Oath of the Trident -

Spell list -

You gain the following spells at the noted Paladin levels -

3rd Level
Absorb Elements, Shield of Faith
5th Level
Calm Emotions, Gentle Repose
9th Level
Protection from Energy, Water Breathing
13th Level
Control Water, Watery Sphere
17th Level
Mass Cure Wounds, Hallow

When you take this Oath at 3rd level, you gain a swim speed of 20ft, and have advantage on Athletics checks to traverse rough waters

Channel Divinity
When you this oath at 3rd level, you gain the following two Channel Divinity options.

Turn the Unholy - As an action, you present your holy symbol and speak a prayer censuring undead using your channel divinity. Each undead that you can see or hear within 30 feet of you must make a Wisdom saving throw.

On a failed save, the creature is turned for 1 minute or until it takes damage. A turned creature must spend its turns trying to move as far away from you as possible, and it cannot willingly move to a space that is within 30 feet of you. It is also unable to take reactions, and for its action, it is only able to use the Dash action, or try to escape from an effect that prevents it from moving. If there is nowhere to move, the creature can make the Dodge action.

Water Breathing - As an Action, you present your holy symbol and for 1 minute, you or a creature that you touch gains the ability to either breathe underwater for 1 minute, or walk on water as per the Water Walk spell for 1 minute
At 15th level, you and a creature that you touch gain this benefit.

Aura of the Trident
At 7th level, you and friendly creatures that are within 10 feet of you have advantage on saving throws against magic from the schools of necromancy and enchantment. You and friendly creatures within 10 feet of you also have advantage on magical effects that charm or inflict necrotic damage.

At 18th level, this aura increases to 30 feet.

Purity of the Waves.
At 15th level, you are always under the effect of a protection from evil and good spell concerning the Undead.

Beacon of the Waves
At 20th level, as an action, you raise your holy symbol and for 1 minute, an aura of ethereal light shines from you in a 30ft radius.

During this time
- You and friendly creatures within the 30ft radius gain 10 hit points at the start of each of your turns.
- You can use your Lay on Hands feature as a bonus action
- All healing spells cast on friendly creatures within the 30ft radius automatically heal the maximum number of hit points.