Intensive fishing and pollution have caused large areas
the sea and ocean to become virtual "deserts". They
have enough oxygen and most of the marine life died
or keeps away.
So here's the idea: Create long floating mangrove islands
connected in large circles, with a small
amount of wave
sea-flow powered air pumps, pumping oxygen into the
water, creating an underwater "conservatory" for fish.
like there are land conservatories for Chimpanzees etc,
but these are undersea conservatories for "regular fish"
and other marine life.
I'm talking about mid sea marine life. No corals.
authority" will also use tethered underwater robots to
the sea from plastic bags.
Within a short time, I'm sure there will be all kinds of
fish and other marine life that will turn up. The place can
then be set up as a safari for rich visitors, or perhaps
growing food in floating aquaponics, with the small
amounts of water loss returned by natural dew.