Homebrew Selkie Species Details

Selkies are seal-people; they resemble humans when not in their sealskin. They always have hair and eye colors that correspond with their seal form. For example, a Harbor Seal selkie would have tan to dark brown skin, darker brown or grey hair, and many freckles or beauty marks on their body. Most, if not all Selkies have dark eyes, which again corresponds to their Seal form. Since selkies do mate with humans, however, there can be hints of the landfolk parentage or ancestry in their physical appearance, like red hair or lighter-colored eyes. Selkies regardless of sex or gender have bodies made for swimming outside of their seal form with strong legs. 
Their organs in both forms are exactly the same resembling a seal making them not exactly human even if they appear to be such. 

Selkies live in small herds lead by the matriarch of their family, they often travel around but have locations they rest in during certain months, Selkies have adapted to build and carry raft like homes the strongest of each herd carry around while the young and old rest during their long sea travels. These rafts are often found in their resting locations and store food, supplies, shelter and young. 

Song and music are incredibly important to Selkie culture, herds often have their own songs passed down for generations that are spoken in their mother tongue, common translations exist but usually aren't as accurate to selkish.

 

Selkie Traits

Aquatic creatures that shapeshift between human and seal.

Ability Score Increase

Your Wisdom score increases by 1, and your Charisma score increases by 2.

Age

Selkies reach adulthood at 14 and can live up to be 150 years old.

Size

Yout size is medium about the same size of an elf when in land form. 

Speed

Your walking speed is 30 however being an aquatic shifter your swim speed is much faster and stronger at 60!

Fey Creature

Selkies originating from the feywild are all ancestors of the feywild.

Darkvision

You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can't discern color in darkness, only shades of gray.

Aquatic Species

 You have advantage on Athletics and Acrobatics checks made in water and you can take the Dash action as a bonus action while swimming.

Selkie Pelt

You are a selkie, child of the sea who holds the skin of a seal at all times. Born in the form of a seal you can shed or put on your skin to transform into a seal. This form gives you stronger, faster swimming, agility and increases the natural aquatic magic connection of the selkies. 
A selkie must always be around their sealskin or they will start to gain disadvantage in saving throws and even lose a small amount of hp depending on how long they've been separated. 

Languages

You can speak, read and write Common and Aquan