An aquatic ranger has a great understanding of aquatic species and the aquatic environment. Their abilities enhance their ability to combat aquatic creatures, enhance their ability to fundction underwater, and at the highest levels gives them mastery over the aquatic environment and the species therein. 

Produced by the marine biologists of the Dugongs and Seadragons podcast.

Aquatic zoologist

At 3rd level, you gain the following features:

Aquatic anatomist

Due to your understanding of the anatomy of marine species, if in combat with an aquatic foes, once per turn, if you hit your foe, you can deal an additional 1d6 damage.

Aquatic naturalist

You gain proficiency in Knowledge (nature) rolls. If you already have proficiency, you gain advantage on rolls related to aquatic species.

Underwater training

At 7th level, you gain a swimming speed equal to your walking speed. As you have a swimming speed you are no longer at disadvantage when making melee attacks underwater. In addition, you can use bows other than crossbows when underwater without disadvantage. Range limits when underwater, however, also apply.

If you already have a swimming speed, you instead gain Evasion whilst underwater.

You can cast also cast any ranger spells underwater without any penalty.

You can also cast Water breathing without expending a spell slot. You regain the ability to do so when you finish a long rest.

Adapted to the deeps

At 11th level, you gain the following features.

Deep sea diver

You are immune to the effects of cold and pressure underwater. Your swim speed increases by 10’ per round.

Ocean senses

Due to your understanding and perception of minute movements and current changes underwater, you gain blind sight to a distance of 60’ when underwater. Because of this understanding of your environment, you also gain the uncanny dodge ability.

Aquatic mastery

Aquaperson

At 15th level, whenever you are underwater, you automatically gain the benefits of the freedom of movement spell and your swim speed increases by a further 10’ per round.

You can also cast control water, water walk, water breathing and charm monster (aquatic species only) without expending a spell slot once each per short rest.

You can talk to any intelligent marine creature and gain advantage on any charisma-based ability rolls against these creatures.

Once per long rest you can also cast control weather without expending a spell slot.