History before Fathom Deeps:
Fathom Deeps was founded by the Transcendent Generation Community, a group of idealists looking for a better, more enlightened way of life on Poseidon. The colonists were ardent environmentalists who believed in peace, simplicity, and looking out for one another. They were mainly Australian, and all human, not because they looked down upon other species, but because their way of life included strict veganism, which was unacceptable to cetaceans. They were highly intolerant of anyone who didn't wholly share their views.
Not wishing to associate themselves too heavily with the other colonists, the Community settled a some distance from Haven. This was fine, since it had been the plan all along and the Community was well prepared. What they had not been prepared for was the sudden disintegration of contact with Earth. They were not a completely independent commune yet, in particular, even between the hydroponics and the little farmland, there was not enough to feed everyone on a completely vegan diet. Furthermore, with the failure of particular plants on Poseidon, the nutritionists discovered that the vegan diet lacked certain key proteins and amino acids. Such a diet would significantly shorten the lifespan of a human.
Much argument ensued, and the harmonious community was broken. When all had been said and done, the Community split up into three groups.
The Idealists: These people insisted on keeping true to the spirit of the Community. Despite the problems and the troubles, they would remain vegan and not give up their way of life. They saw the current situation as a test of their ethics.
The Centralists: The main view of the Centralists was that the colonists, both Community and outsiders, would only survive if they worked together. They wanted to increase contact with Haven and rejoin the rest of the colonists. They would give up veganism and make whatever other adjustments to their lifestyle as were necessary for their survival.
The Pragmatists: The Pragmatists also believed it was time to adjust their lifestyle, but weren't willing to go as far back into mainstream culture as the Centralists. They proposed a sort of balance between need and nature, inserting themselves into the food chain without breaking it. Eating a few fish wouldn't destroy the environment as long as there were enough to procreate, and it was the responsibility of those who chose to eat fish to make sure no ill effect came of it.
In the end, the resources of the tribe were divided between the three groups: the Centralists stayed and kept the houses and lands, the Idealists left and took the hydroponics, and the Pragmatists left and took the underwater equipment. The Pragmatists established their own village, which they named "Fathom Deeps".
The Founding of Fathom Deeps:
The leader of the Pragmatists was an accomplished oceanographer who believed that the colonists were not using their aquaforms to full advantage. He designed Fathom Deeps to be an aquatic village. It was built in a mangrove forest, using the trees themselves for support. The houses were built tall and narrow, some with only the top floor above water at high tide. The lower floors had only netting for walls, so the current could flow freely through them and not knock them over. The roofs were utilized for gardens. Fathom Deeps is located in the Cays, off Kauai.
Seeking some sort of grounding for their new, adjusted philosophy, the villagers erected a pillar in the center of the village. At the top was written: "We, the People of Fathom Deeps, take Personal Responsibility for Our Effect on the Environment." Below those words several columns were made to track the condition of the environment over the years. There were columns for population growth of the village, of various types of fish, the condition of the water, and other data.
Culture:
The people of Fathom Deeps still take the environment very seriously. More pillars have been added to keep track of data, and this information is kept scrupulously up to date. The data is used to calculate what the village must do to have no adverse effect on the environment. Sometimes the village grows a certain type of anemone to help clean the water. Sometimes hunting a certain type of fish is banned. At one point, many of the fish became scarce, and the villagers stopped eating fish at all. A few became sick and one died. A famous quote of that time was "It is better that a few of the ancestors die than all of the descendents perish."