Marilyn, Ursula and Savannah were officially the first inhabitants of what was optimistically called Saba City. Their home was a design by Sas, in essence a large round thick tarp, anchored to the ocean floor, then partially filled with air that caused it to expand upwards in a half bubble. They mainly lived in the lower, water-filled level, but upstairs was a dry area for electronics, like a computer, a TV and a microwave, with electricity, airhose, cable and internet services provided by the Saba utility company. Total cost for an underwater home was less than twenty thousand dollar.
With the startup costs to live in Saba City much lower than any city on land and the prospect of exploring the vast secrets of the ocean, many pioneers inquired with the Saba government for a chance to live in the new city. The only requirements were that the person qualified as a human based underwater creature, or a HUNC as they were soon called, and accepted that legal status, plus the person needed to present a plan to sustain their ability to live underwater. Basically what job did they plan to do.
Kaz had ideas for a much simpler version of a HUNC, but he could not handle all requests by himself. So he invited neurosurgeons and likewise specialists from all over the world to setup practice in Saba. His labs expanded soon while teaching his colleagues the ropes. Marilyn had a full-time job now assisting Kaz in developing training materials plus she was life proof of one of the possible end products. The transformation of the four original mermaids was used as a blueprint for future "clients".
As said before, it was not enough to just strap on an OxyConv and start living underwater. The transformation to HUNC had to be made and adding webbing between the fingers and changing the feet to flipperlike appendages, plus adding a temperature resistant layer of skin and feeding the OxyConv output straight into the airways, qualified as a much cheaper alternative than a full tail or tentacles. Maybe they were not even half as fast as one of the mermaids, but many chose it as a path to at least settle in the city, with hopefully a chance later to undergo a more severe transformation.
Within a decade Bubble City, as Saba City was affectionately nicknamed, reached a population of twenty five thousand, expected to double in only half that time. A lot were farmers, growing different versions of seaweed, which was used as a base for many dishes. Fish farms provided the necessary meat although old fashioned fishermen would roam the oceans for tuna and other delicacies. A water factory was developed to extract fresh water from ocean water and experiments were ongoing to generate electric power from ocean currents to become more self-sufficient.
On the island the population had grown similarly. There were hundreds of thousands of ongoing requests still to transfer to HUNC status and medical skyscrapers were built to handle all these requests. The more expensive traditional mermaid form was now the most requested with the octopus version a distant second, yet very popular with farmers, for the extra "hands". Kaz and Sas were billionaires by now and Marilyn close behind. But they invested all their money in further development of Saba City and a few more underwater cities that had started off the coast of other islands, which had chosen to submit to Saba law.
The United States finally passed laws that recognized HUNC's as a species equivalent to full humans. Not much later the United Nations followed suit. New laws were developed to control the expansion of underwater cities. Coral reefs were protected and for every underwater home built an equal amount of reef needed to be added.
The cities installed their own government and although technically still under Saba rule a reversal of political power took place. Saba City was officially recognized as the new capital and all governmental functions and buildings were moved underwater and ran by HUNC's. In a declaration of recognition of the new sub-species a set of new ground laws were defined. The first law declared all HUNC's equal, independent of shape, gender, age or original race. The second law recognized the original human species also as equals. The third law declared gender non existent as physical differences again did not matter. A number of laws were designed to protect the environment, fight pollution, restore underwater nature and limit the exploration of natural resources. And finally, with Saba now being the medical capital of the world any DNA and stem cell research to improve the HUNC species was stimulated and often sponsored.
Ursula, as one of the original founders, went from coral reef chief to director to minister of environmental matters. She was very much involved in designing the environmental ground laws. And from young age Savannah and her sister Lauren were part of cleaning missions, targeting the tons and tons of plastic garbage dumped into the ocean. Under guidance of Sasha and with funds provided by Kaz and Marilyn the plastic was repurposed as the base material for new living bubbles and for the first time in centuries the "human" expansion actually resulted in a cleaner world.
Life at the new frontier was tough and there were plenty of casualties. Mostly through confrontations with sharks or killer whales, but also because of poisonous fish and plants. Human nature would demand that all sharks should be killed, as proven through hundreds of years of evolution. But HUNC's did things differently. They acknowledged the need for wild animals in the eco system, so rather than killing them they found ways to reduce confrontations. Stink buoys and whale sound simulations kept the killers away from the cities and the farmlands.
Savvy was the first of the second generation of mermaids and her sister Lauren one of the first of the new generation of octogirls. Neither had ever lived on land and for them swimming and floating was as natural as running or biking for a human kid. School was often hands-on experience in farming, fishing, environmental cleaning and defending.
The two of them were out in the coral reef as Lauren had to do a paper on different species in the reef. She had to identify at least fifty. Savvy had done this long time before and she spent all her free time in the reef, like her mom Ursula, and she knew she could easily identify five hundred species. She also knew the amount of species she couldn't identify was still even bigger. Since the HUNC's had settled on the ocean floor the coral reefs had never been healthier and she took personal pride in that achievement.
Lauren was more book smart, like their other mother, and she was already fantasizing about when she had her own lab. She knew the evolution of their own species was still very artificial and she agreed with the conclusions of her mother Marilyn and her grandpa Kaz that DNA research would eventually lead to true natural underwater beings. She had read every book on this subject in their own dry area, and many in the library, where other kids her age would read fairytales and comics.
But no matter how smart she was, the paper had to be written. Her sister pointed out different species in the reef and she made pictures with her smartphone and made notes. As was everybody's habit underwater they kept an eye on everything around them, including what may be swimming above or below you. And when Lauren saw a shark swimming in their direction she pointed it out to Savvy. Savvy had seen the animal long before her and told her not to worry. They were too big for this type of shark, but just in case they kept a hand on the sheath holding their knife. Savvy had a black belt in sharkate (pronounced very similar to karate), as the new martial art was called, that taught about one-on-one combat with dangerous animals. But her sister was still learning and this type of fighting can't be obtained from just books.
When Lauren had her fifty species Savvy decided to celebrate by showing her sister a secret. She'd found some caves under the reefs and in one of them she kept her personal treasures. It wasn't easy to get there, as a matter of fact Savvy worried that when it was her turn to get her final sized tail in about five years, she may not fit through the tunnel anymore leading to her cave. But that was a worry for later, right now she could still handle it, though puberty started showing on her chest. It was totally different for Lauren, her body was extremely agile, some of her tentacles reaching forward and pulling her through while others pushed her.
The cave was magnificent and Lauren stared with huge eyes after Savvy had made some light. There was all kind of jewelry and golden coins and Savvy explained how she had found some shipwrecks under the reefs and to prevent people from ravaging the so important nature she'd taken out everything valuable and hidden it here. She gave her sister a golden bracelet and a diamond ring as a reward for completing the dull task earlier.
She knew their moms would not ask questions as they were aware of the existence of the treasure cave.
There were also some beautiful shells, that Savvy had found as a kid, plus a mirror and a makeup set. There was a smaller cave with an airbubble and Savvy showed her how to put the makeup on, only to lose it when they got underwater again. They had some fun trying on some of the dresses that Savvy had found as well, but in the end it was too restrictive to be practical. In the end the most "valuable" possession was a sturdy hairbrush, and they used it to do each other's long hair.
The main lesson that Lauren learned that afternoon was that there's more in the reefs than just plants and animals. And some of it has a high value for humans, though not so much for HUNC's. And there were enough examples in the books that Lauren had read to know that some humans would kill to get their hands on a treasure like her sister had hidden away.