Great job with this piece!! I'm going to tell you my suggestions first, and end with all my compliments, so I end on a happy note. (Yeah, you're probably thinking, "Why doesn't she just get to the critiquing already!!?" You're right- I am terrible at getting to the point.)
My only suggestion is to choose something a little more original, and creative. Something that hasn't really been done before. You did a great job with this- don't get me wrong- but the whole "swirling into the middle" thing has definitely been done before.
On the contrary, you applied original concepts into the common idea, making it yours. So, in the end, what I said about it not being a very original idea may just be me running my mouth.
Now, you may be saying to yourself, "What kind of original concept is she talking about?" First I like the colour combo- Peachy/orangy tone with various blues and some greens- it came out better than I would've expected it to. Orange and blue are complimentary colours, so they don't look so great when mixed, but the way you overlapped them mixed them the perfect amount before they started looking icky. So, job well done.
Just the fact that you sort of "overlapped" the colours was a creative concept. Most people either completely blend the colours or they make one colour stop when another starts. You gave those areas a translucent effect so that the top colour was see-through and you could see both of them clearly. Good job with this part!
The name- Poseidon- was appropriately chosen for a few reasons that I'm not sure you actually meant. First the colours- a sandy colour with an ocean blue. Poseidon is te greek god of the sea and water and all things of that sort, so the name fit the colours well. Also- the design. It looks like seashells (to me) where smaller swirls are on the biggest swirl. Once again, Poseidon is the greek god of the sea, and seashells are the shells of the sea...you know where I'm going with this.
Before I bore you to death (which I may have already done) I'd like to just congratulate you on a job well done. This piece is truly beautiful, and you should be very proud of it. Great job!!