Hello, I am practicing to be a level judge, so here I go...
I think your level was very interesting. I like how you have go through multiple tunnels in order to to get all the star coins. I think the layout of the level was OK. I wouldn't say it was great, because some of the tunnels were very... squishy. Therefore, it was a little hard to get around the level. Also, the level is lacking enemies. Even though you have a good amount of enemies, there still could have been more. However, if you were aiming for a easy type of difficulty then it is about right. If you were aiming for something harder, then you should add a bit more enemies around the level. Another quality I noticed it was missing, was the fact that, there were no background objects at all. (correct me if I am mistaken...) If I were you, I would add some seaweed or something similar to that... Basically, some aquatic background objects...
This level could still use some work, but other than that, I had a good time playing it and was glad I did. All that is left to say is... Keep making those levels!
