When the creature is submerged in water their legs transform into that of a mermaids tail.

When in water, the Giga Mermaid can choose to achieve her Giga Form. In this form the Giga Mermaid doubles their size. The creature can use the gem on her head to cast Scorching Ray five times per long rest. The creature also has Advantage on Strength Checks and Strength Saving Throws.

Your Strength, Constitution, and Dexterity scores each increase by 1.

Giga Mermaids reach maturity around age 20 and can live up to 400 years.

Tritons are slightly shorter than humans, averaging about 5 feet tall. Your size is Medium.

Your base walking speed is 30 feet, and you have a swimming speed of 30 feet.

You can breathe air and water.

You can cast fog cloud with this trait. And starting at 5th level, you can also cast wall of water with it. Once you cast a spell with this trait, you can’t cast that spell with it again until you finish a long rest. Charisma is your spellcasting ability for these spells.

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 beasts have an extraordinary affinity with your people. You can communicate simple ideas with beasts that can breathe water. They can understand the meaning of your words, though you have no special ability to understand them in return.

Adapted to even the most extreme ocean depths, you have resistance to cold damage.

You can speak, read, and write Common and Primordial.