If Cyl Sea & Ring Sea had avg. depths .5km, this means the ocean water volume taken from Earth would take 3.94cm ocean depth, (about half the length of your finger). That's hardly noticable, but Earth folks living at ocean coasts approved having even that little water disappear off Earth, since recent Solar warmed melting of mountain or polar snow and glaciers had been raising the levels of Earth oceans more than that. That had been becoming an ever worse problem for some coastal cities etc.
Some settlers better educated for existing ocean and island life forms took the lift down. Available to them below were vehicles they could ride to a distant ocean coast. As lots of pipes got sent down, they got them suitably joined, reaching out some from the coast into the ocean. They properly screened the open end there. Helped by some new approved future settlers still on Earth, they got water pumps working well. Ocean water could now start being sent up for Cyl Sea. With Solar light kept blocked away, the water would for now freeze above into big ice chunks being collected, awaiting Cyl Sea completion.
These current and future settlers spent weeks exploring what seemed to be better places for gathering many wanted good transportable sea and island animal life sample varieties. Some could be sent up simply as eggs or embryos to be carefully developed into properly nourished new young for the new Cyl Sea or the later huge Ring Sea, and for their islands.
Seed varieties were also collected from wanted near-ocean plants. These were sent up and planted in the high settlements. Later these would be replanted in the completed Cyl Sea, or later in the completed Ring Sea.
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