The Sea Domain for 5e clerics

Here's a custom domain for your 5th edition clerics, for if the Tempest domain isn't your god's deal.

Sea Domain Spells

Cleric Level - Spells
1st - Create or Destroy Water, Swim*
3rd - Conjure Vessel*, Gust of Wind
5th - Water Breathing, Water Walk
7th - Control Water, Evard's Black Tentacles
9th - Conjure Elemental (Water only), Drown*

Bonus Proficiency

When you choose this domain at 1st level, you gain proficiency with vehicles (water), heavy armor, the trident, and Strength (Athletics) checks. Heavy weight (including armor) won't hinder you while swimming and can't drag you underwater unless you choose so.

Channel Divinity: Master of Water

Starting at 2nd level, you can use your Channel Divinity to charm creatures with a water theme and turn creatures with a fire theme.
As an action, you present your holy symbol and invoke the name of your deity. Each water or fire related creature that can see you within 30 feet of you must make a Wisdom saving throw. If a water themed creature fails its saving throw, it is charmed by you for 1 minute or until it takes damage. While it is charmed by you, it is friendly to you and other creatures you designate. If a fire themed creature fails its saving throw, it is turned for 1 minute or until it takes any damage.

Blessed Lungs

At 6th level your god turns you amphibious. You now can breathe air and water.

Strike of the Crashing Waves

At 8th level, you gain one superiority die (a d6) and know the Pushing Attack and the Trip Attack maneuvers.
When you reach 14th level, you gain one additional superiority die and the dice increase to d8.

Avatar of the Ocean

At 17th you can transform into a Water Elemental once per long rest. This functions as a druid's wild shape.

New Spells:

Swim

1st-level transmutation
Casting Time: 1 action
Range: touch
Components: V, S, M (a cup of salt water, which needs to be consumed by the target)
Duration: 1 hour
The touched creature gains a swim speed equal to their land speed and automatically succeed Strength (Athletics) checks to swim in rough water.

Conjure Vessel

2nd-level conjuration
Casting Time: 1 action
Range: 3 feet
Components: V, S, M (a ship in a bottle)
Duration: 8 hour
You summon a boat suitable for coastal and river navigation. It can carry up to 8 medium sized creatures and disappears after 8 hours. If this spell is cast again before the spell is ended the duration is extended by 8 hours.
At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, you summon a vessel suited for open sea travel complete with (non-combatant) ghostly crew.

Drown

5th-level necromancy
Casting Time: 1 action
Range: 30 feet
Components: V, S
Duration: Concentration, up to 1 minute
You fill the targets lungs with seawater.
The target must make a Constitution saving throw. On a failed save, the target starts suffocating for the duration. At the start of each of the target’s turns before the spell ends,
the target must succeed on a Constitution saving throw or continue being suffocated. On a successful save, the spell ends.