Vent fields are really nice for our r&d phase because the hot fluid is so close to the surface and very little drill depth is required, but they're actually quite poor for commercial scale generation due to: complex topology, sensitive ecosystems, active volcanism, and lack of sedimentary cap. For commercial scale generation, it's better to be a few km off axis and away from the vent fields where you can have 10s to 100s of meters of sediment that acts as an insulating layer for the reservoir. In those off axis sedimented areas life is extremely sparse.