For me I think I'd crop it more landscape. Leave the sand in for sure. I know you'll lose some of that heavy, dramatic sky but you can get that back with some creative burning.

I'd look closely at the tone/curves as well. That might help lift those dead looking greens a little. This was a good candidate for an HDR or similar trreatment.

As a rule I usually shoot landscape shots as landscape instead of portrait for a few reasons. One is most of the photos are displayed on a monitor which is ... landscape. That makes the photo more impacting right away I think.
The other reason is there is usually more to see around the scene rather than top and bottom (always exceptions to the rule though of course) and lastly, if I take it landscape then I can usually crop it portrait later if I want but it's more difficult the other way due to not catching as much scene laterally with portrait.