Hot smokers! We actually drill down to the river of geothermal water circulating this planet, and cover the bore hole, with porous cone impregnated with extremohile bacteria. That use geothermal steam in place of sun light to do photosynthesis.
Cm(H2O)n=carbohydrates – the material of life Cm(H2O)n
Hence haemophilic bacteria support missive ecosystems. Which feed animal algae, which feed wish, which feed man.
So we create a hot smoker ever ½km along the geothermal river, where there is no nature hot smokers. Black smokers also seep out C – so they are a potent source of cheap carbon brickets.
So hot smokers fill up with heavy metal dust – gold, platinum, silver and copper. So we we crop inactive hot smokers down to 2 feet of the sea floor, we gain access to material richer in gold than the most lucrative wined ore.
We sell the rock on to metals companies, and they pay us for the heavy metals recovered. Just so much nearly free gold.
Erecting artificial hot smokers, will increase life in the seas – and so fish stocks. And we get silly amounts of gold and platinum.