This is a reluctant recommendation of the game in its current state of developement.
I'm reluctant to recommend because I'm finding it difficult to get excited to play the game and I'm finding its limitations of movement to be frustrating.
You can't alter your axis and swim sideways which can be very odd underwater especially when swimming along the length of a sunken ship. I'd like to be able to turn to face the ships orientation and drag myself along certain objects and the lack of this makes that freedom of being underwater further away from how you actually feel in the game.
The most frustrating part for me is that I see this as an MMO, not the usual MMO though, it's a Massively Missed Oportunity. If you've ever watched the TV show 'Tanked' you'll likely know what I'm getting at here. The living eco system in our seas is sorely missing from this game. The graphics are more in line with those aquariums in the show where the customer doesn't have enough time or knowledge to be able to look after a 'real life' aquarium with living rock and coral being substituted with acrylic, silicone, rubber, painted pieces that are too bright and unnatural.
This may be ok for some but for me I'd like to see something closer to a real life reef than the artificial reefs that are used in that show. This day and age I think the devs could aim higher with transparency brought into the fray and annemonies and corals showing some real colours and movement, not these bright pink and blue stuck on cheapo immitations.
Under water there's a lack of distance viewing which should have been an opportunity to really cram the details into the surrounding area of your swimming zone. I can't help but feel that the Unity 5 engine may be partially to blame for the lack of this. But I live in hope that the life that is sorely missing for me will be gradually introduced over time with this being still an early access release.
From a lifelong marine tank enthusiasts perspective I can't help feeling really disappointed with the lack of realism but at the same time I do enjoy the game, so I have to give it the recommendation for that reason alone. I hope that over time the realism will be introduced to bring us a game that really uses current pc capabilities.