Nice track but there are a couple of issues to my ears that, if addressed, would make this a very good track. I would consider it for cruise/travel videos.
First, the shaker suffers from some combing. Not sure if that is intentional but I would go with a more traditional sounding shaker/maraca sound. As it is, it is a bit distracting. I would also consider bringing the volume on it down a bit.
I would consider a beat of silence followed by a kick in to the main theme.
While I know that delay and reverb are part of the summer sound, I think you might have a bit much going on here. It sounds great on the mallet keyboard sound and the lead synth, but I might consider toning down on the snare. I think there are too many elements with noticeable reverb on them and the mix loses clarity.
Hope this helps. Nice work.