"I'd like to be a mermaid".
"Molly we didn't bring our swimsuits and as mermaids are-" Jane started to complain at the choice. "relax mrs Scott we're covered for that. mandatory for your daughter, optional for you" Dr James kindly interrupted before requesting "that said I'd advise stepping back a bit first".
no sooner had the family did as asked dr James had inputted a few commands into this terminal within the room. the first course the floor to open out a diving like pool within the centre of the room, the second brought out a hidden rack holding bikini tops made out of a pair of seashells and seaweed straps each. "management detest young female guests going about topless in human-like transformations" dr James then admitted "anyhow one your daughter is properly covered we'll being the process".
once Molly and Jane were wearing a seashell bra each while Carl was waiting about naked "now to get these pigtails out then" Jane announced. "oh they are fine, only nymphs can't wear such accessories but if you want to later you can exchange the hairties for seaweed versions" dr James assured. "we can shop underwater?" Carl questioned. "it'll be charged to you when your return here to be charged back" dr James responded.
once the Scott family was ready and seated at the opening "here you go" dr James called as he handed each Scott a wired looking drink. "and these are for-" Carl started before he and Jane watched Molly take her own drink down in one go. "well your about to see now" dr James responded. Molly meanwhile felt it and took joy as her legs were locked together, her toes growing and splitting into branches under the water, her legs then merging into a single limb as gray scales started forming from her waist and spread downwards, a light gray membrane then forming between the branches that had been her toes to create a tailfin and finishing off her new tail, just as she felt her lungs alter somewhat and a layer of sorts formed over her eyes.
"AH COOL. THIS IS AMAZING" Molly called out in joy at the results. "so drinking these will make us merfolk" Jane remarked. "well... bottoms up then" Carl returned as he and Jane followed Molly's lead and underwent the same process. "now then, Jessica should be waiting for you just outside the tunnels linked to the opening here to help guide you through being merfolk" dr James then announced. "got it" both Jane and Carl accepted while Molly merely dived into the water, her parents close behind.
"THIS IS GOING TO BE THE BEST BIRTHDAY EVER" Molly called out in joy while swimming ahead, taking equal joy at the feeling of breathing water like air. "who's idea was it to give her all those swimming lessons?" Jane meanwhile complained as she and Carl legged behind. "better safe then sorry you know" Carl defended as they reached the exit where a mid-30s raven haired mermaid without a seashell bra was waiting "ummm... you must be Jessica?" Carl asked in discomfort at the naked woman. "Yes indeed folk. your guide to the realm of undersea like as merfolk" Jessica agreed.
"ALIGHT. where do we start?" Molly pestered in her youthful joy. "now now little one" Jessica started: