I have followed this off and on. For those wondering, TMC [1] is one of the primary companies on the forefront of this. Similarly, the main body in charge of regulation here is the International Seabed Authority [2].

I'll be honest, I don't know how I feel about it. TMC has taken the position that it is potentially better to destroy seabed ecosystems than land based ones with strip mining. (at least that is my take on their position) There is truth in the idea that picking the least bad solution is the responsible thing to do. We will keep mining for these resources so where should we do it? The problem is the unknowns. Effectively, I believe, they are arguing that the unknown dangers are still better than the known damage we do with traditional mining. The sea is a big place after all. Of course they are clearly biased in their thinking since the potential profits here are just staggering so staying objective with hundreds of billions of dollars staring at you is very hard.

A major change in the arguments about impact came with the study that showed the potential for oxygen generation by the nodules being mined. This so called 'dark oxygen' [3] could be a major part of the ecosystem at those depths. Oxygen is really scarce so anything that produces it is likely crucial. I personally don't have a background anywhere close to that required to critique the science around this but it looks interesting and is definitely worth following up on.

The chemistry of these nodules is also interesting but the bottom line is that once they are mined they won't come back. They take a long, long time to form. Like 2-5 mm per million years [4] slow.

Up until the dark oxygen research the main concern was the plume that mining created and what effects it would create on the ecosystem as a whole [5]. There were, and still are, a lot of unknowns about how big it could be, how long it will stick around and the impacts it could have.

Basically, there are a lot of ecosystem unknowns here so weighing the potential impact to the ecosystem from this vs the real, and devastating, impacts from mining on land is a very hard thing.

[1] https://metals.co/ [2] https://isa.org.jm/ [3] https://www.smithsonianmag.com/smart-news/scientists-discove... [4] https://en.wikipedia.org/wiki/Manganese_nodule [5] https://phys.org/news/2025-03-deep-sea-sediment-plumes.html