For vehicles, I would say any one group from our lists. Very little wheeled, no oared, some sailing vessels on the Sea of Silt.

Just remember, any spell requiring water components I will be requiring a check. ie. they will not always be successful. Summoning water and particularly ice (not really thematic at all) will be difficult :)

Cantrips: Resistance, Hydraulic Push or Primal Savagery (PCC) ?, Shape Water (XGE)?
Domain Spells: Create or Destroy Water, Purify Food & Drink
1st Level Spells: Absorb Elements (XGE), Ice Knife (XGE), Snare (XGE), Bane, Bless, Cure Wounds, Detect Magic, Guidling Bolt, Protection from Evil & Good, Shield of Faith, Quick Breath (PCC), Animate Water (PCC)

Not sure about Domain power as per the en5ider article as they are water vehicle prof, swimming = land speed & double prof in swimming/floating.

1. Ability score bonuses as half-elf.
2. A Background.
3. Racial Drawback penalty. (See elf on the Athas Major Races Page). Then a bonus proficiency for each of the racial drawbacks listed.
4. The 12 cleric spells and two appropriate water domain spells. (Remember there will be checks required for water spells).
5. Cleric skills: Cleric class page
6. Cleric weapon group proficiencies: Cleric class page
7. Whether you want to take other Drawbacks and then any proficiencies or feats for taking these.
8. A picture. (Feel free to upload to PC Page).
9. A name.
10. I will do your wild talent randomly.

Your PC stats have NOT been modified for half-elf as of yet. See the Athas Major races Page).

In posts below I will ask for your other choices.