You are not understanding how seaweed farms work. Dry areas are required for logistics and as a safety vault. You need space for storage. Space for wintering.

You are not understanding how seaweed farms work. Dry areas are required for logistics and as a safety vault. You need space for storage. Space for wintering. Space for each machine that you need to process the production. And drying algae smell. And if you have a big storm alert, you will need to rush to move a huge volume of stuff, cords and algae safely ASAP to the coast and keep there for several hours. You can't just put this in the closest hotel terrace. There is a lot of things that a sea farm needs to survive. And there is a huge load of legal issues, because the sea is not a "free for all" space. Is a high skill / high luck and deep pockets activity. Why could be a big company be interested in this? Well, If you have the money you could culture much higher value products in the same space, right?. I would speculate that is a combination of being able to obtain government aids + real state grab. I can be totally wrong about it, of course.