Here are just a few ideas for Mermaid Games to do at parties and small functions.

Mermaid Games for Dry Events

Mermaid Says:
This game is the same as Simon says. Mermaid Says is for 3 or more players where 1 player takes the role of "Mermaid" and issues instructions (usually physical actions such as "jump in the air" or "stick out your tongue") to the other players, which should only be followed if prefaced with the phrase "Mermaid says", for example, "Mermaid says, clap your hands". Players are eliminated from the game by either following instructions that are not immediately preceded by the phrase, or by failing to follow an instruction which does include the phrase "Mermaid says". It is the ability to distinguish between valid and invalid commands, rather than physical ability, that usually matters in the game; in most cases, the action just needs to be attempted.
This game is good for younger children.

Ships and Sailors:
Tell all participants to stand in the middle of the room facing the leader who is in the front of the room. Explain that all participants are sailors and they are all on a ship.

The mermaid will play the roll of the captain and call out orders. Players who don't do the actions quick enough or who break from character are out. Once the captain calls an action, each player has 3-4 seconds to start performing the action. If they don't find a group fast enough or perform the right action, they are out of the game.

The Captain will give a series of orders. Any sailor who cannot complete the order correctly in a timely manner is out and must sit down on the side.

The orders and their explanations are as follows:

Go West: All must run to their right.
Go East: All must run to their left.
Hit the Deck: All must quickly lie on their stomach.
Captain's Coming!: Everyone stands at "attention" (in a salute), and they can’t move
from this position until the caller says, "At Ease!" If they laugh or break from the
attention, they are dismissed.
Mermaid spotted: Sailors must find a partner. One person drops to one knee the other
stands behind them, puts a hand on their shoulder. Both scan the ocean for the mermaid.
Three Men Eating: Sailors are to form groups of three and sit down in a circle. Next
they are to cup as if to hold a plate and scoop with the other hand quickly as if to feed
themselves.
Four Men Rowing: Sailors are to form groups of four and sit in a row on the floor. They
are to swing their arms as if they are rowing.
Walk the Plank!: Five people stand in a single file row hands on the shoulders of person
in front of them

Because it is more complex, this game is good for older children.

Mermaid Games for Pool Events:

Treasure Dive:

The mermaid will throw treasures (sea shells, dubloons, dive rings, etc.) into the pool for children to dive for and recover. This game is only for adept swimmers.

Ring around the Mermaid:

Using a large hula hoop, children will stand on the edge of the pool and try to toss the ring around the mermaid.

Balloon toss:

The mermaid will blow up a balloon. The goal is to keep the balloon in the air without letting it hit the water by hitting it upwards with arms, hands, and heads. Everyone will participate to keep the balloon air bound. This is a fun, noncompetitive game.

If y'all think of any other games for parties, please add them here