I've been on a pump for 15 years and LOVE going to the beach! First things first- these pumps are NOT water proof. They tell you they are but they are not- first time I took mine into a pool it died, then I heard a question I had never heard before "what is you back-up Insulin plan?" ummm what? My back up insulin plan was me giving myself 1 unit novalog shots every hour until my new pump arrive.
So, for bathing suit season my insertion site is way below my waistline, so make sure you have that going for you. I always bring a small cooler with a frozen water bottle or ice pak with me to the beach or pool for the coolant. When I'm vacationing, I just grab ice from the hotel (if I'm lounging all day at the beach I make several ice runs as needed) I always bring several sandwich sized ziploc bags with me to the beach and when I'm traveling so I can put my pump IN the ziploc bag IN the cooler while I'm attached to it. I snake my tubing out of the top of the cooler (cooler lid is not completely closed) right to my beach chair where I'm sitting (usually through the side under the arm, whichever way uses shortest amount of tubing). If I want to lay down on a towel the cooler comes with me. I find this keeps the pump nice and cool and helps keep it out of the sun and sand.
I disconnect my pump to go in the water- lesson learned there- and give myself a little bolus to cover for the time apart from my pump. I always make sure the screen is never touching ice, only the insulin side. This has served me well over the last few years while living in South Carolina and going to beaches in Florida. I'm going to Kauai in March and will be using this same cooler technique.
When I FIRST started a pump I was living in Las Vegas and playing beach volleyball- my pump buttons melted off- so using a coolant of some sort is key to prolonging the life of your pump. Always put your pump in a Ziploc bag though, even if your ice is already in a bag.
If you come across any products that might be more helpful than the good ol cooler and ice pak, please let me know.
I hope this helps :)