#3 - I like the idea of the C's facing each other, but I don't like the diamond shape at all. I think diamond is very overdone in logos. If you want to do something with the C shapes rotated to make an S that would be good to see. I'd also love to see something that's more of a wordmark logo
I'd like you to make the two dolphins become the O in the logo and drop the line in between the picture. To make a round circle of dolphins it may mean 3 smaller dolphins for the O. Thank you for listening to my feedback