Hi Rosa, I really like your banner and the trees, they are matching with each other and it is very tropical. Also, the shape and colour of your dolphin are so smooth and astonishing. I think it will be good if the eyes can be bigger - it is just my personal preference - I like cartoons with big eyes and I found them so cute :)
Overall, I think it is a good user design with lots of details in the object!
Cheers
Rosanna