[lumost]

One of the Main limiters with underwater intelligent life would be industrialization. How are you going to use a steam engine underwater? What do you burn to heat it? Given that geothermal vents would be the source of life for such a species - capping them for machinery would also be unwise.

[awb]

Any motion can be used to do work. If there are underwater currents, that power can be captured and used.

[polishdude20]

Why would geothermal vents be a source of life after the species has evolved reproduction?

[pc86]

In the same way our sun is for us. Life on Earth wouldn't last very long if you plopped a Dyson sphere between it and the sun.

[PaulHoule]

Source of energy and materials…