Arielsa

Arielsa is the femslash ship between Elsa and Ariel from the Disney fandom.

Canon
As Ariel and Elsa are from different series, they have never met. While Ralph Breaks the Internet has online versions of the two known as "netizens". In the film, after Ariel emerges herself from the water spiral, she joins Elsa on Jasmine's magic carpet, before Elsa uses her ice magic to freeze the water spiral. As Pocahontas uses the wind to send Ralph to a bed to land on, Ariel moves from behind Jasmine to the front of Elsa before she sings. In Once Upon A Time, Elsa unknowing traps Ariel in a bottle while she is trapping Blackbeard's crew.

Both Ariel and Elsa have fathers who are the leaders of their people and who want to keep their daughters safe. The two had lost their mothers while they were in ship wrecks. The two have also worn a blue, sparkling dresses that were created from magic. For a brief moment in their Disney films they are seen on a rock that sticks out above the ocean's waves. Before Elsa's goes to take the Nokk's trail, she steps into the beach bear foot as she gets ready to run across the ocean's surface, while Ariel has walked bear foot on the beach around Eric's castle. Even though Ariel doesn't have any magical abilities like Elsa, one of the episodes in the prologue TV series of Disney's The Little Mermaid did have Ariel becoming a Sea Sorceress for a short time until she wished her new magical abilities away, when they got out of hand and put one of her friends in danger. Just as Elsa's ice powers put her sister and kingdom in danger until she used love to reverse the unattended harm and damage.

The two have also brought two worlds and two types of people together, along with them leaving their childhood homes so they could start anew in the land that they helped their original home kingdoms make peace with. As Ariel's permeant human form allows her to be with the man she loves, while Elsa's new duty and role as the fifth spirit of the Enchanted Forest has her as the guardian and bridge between the magical and mortal worlds. Much like how Frozen II has Elsa meeting, taming and befriending four magical beings of the elementals, the Little Mermaid TV series has Ariel meeting and encountering other kinds of magical beings that reside in her underwater world along with her seeing the good within certain kinds of sea animals and people that many others have deem as dangerous. Along with the show having Ariel riding on the back of a giant Seahorse, while Elsa taming the Nokk had made the water spirit her personal steed.

Fanon
Elsa and Ariel are shipped by a small group of fans who believe they would get along very well. Along with the fact that both Disney Princesses are extraordinary, talented women. Elsa's ice powers and Ariel's beauty singing voice. Because Ralph Breaks the Internet is a canon Disney crossover, that has a version of the two know each other, the ship sometimes has them in the modern, casual style clothes that the netizen versions of them wear in the film. After the teaser and official trailers for Frozen II were released and showed the scene of Elsa running barefoot across the ocean's surface, the ship became much more popular from the water related scene inspiring a few fans to write and draw Ariel helping or coming across Elsa after she falls into the water and encounters the mermaid instead of the Nokk.

On AO3, the ship has 11 fanfics.

Fandom
FAN FICTION
 * Ariel/Elsa (Disney) tag on FanFiction.Net
 * Ariel/Elsa (Kingdom Hearts) tag on FanFiction.Net
 * Ariel/Elsa (Once Upon A Time) tag on FanFiction.Net
 * Ariel/Elsa (Once Upon A Time) tag on FanFiction.Net

TUMBLR

Trivia

 * The group photo taken with Vanellope, in the trailer for Ralph Breaks the Internet, Elsa is seen above Ariel.
 * The two are from two of the few Disney films that have become Broadway shows. As well as them being featured in the Disney on Ice show.
 * They are two of the limit time characters, with their own limit time clothing, in Disney Magic Kingdoms.
 * They are two of the Disney Princess characters who met Sora in their own home worlds in the Kingdom Hearts series, as well as both of them appearing in the same game, Kingdom Hearts III.
 * Elsa is the oldest sister while Ariel is the youngest.
 * They each have two castles.