There is a Richard Scary book about going on a plane ride, good to look at before you go.
Dress in comfy clothes for the plane and take a spare top for you and full change for him
Run him like a maniac before you get on the plane, find an empty ish gate and literally run to the pillar and bunny hop back, run to the window and star jump back. You want him nicely exhausted before you board.
Take a sippy cup with a valve for take off and landing. The valve will stop spilling, but having to suck hard will equalise his ear pressure. Also take a lollipop in case the drink isnt wanted.
Consider reins if he is a bolter
Soft sand shoes are useful as the paving around the pools can get really hot and they can be worn into the pool
Find out if the resort provide beach towels
Find out if you can launder clothes at the resort, and if you can take a little baggie of washing powder
Take lots of snacks
Dont forget the lovie/blankie and a spare