1) Good sunblock - it's very important to get a physical sunblock for your little one vs. a chemical sunscreen. Check out this list from the Environmental Working Group to find one that doesn't contain potentially harmful chemicals or toxic ingredients. We use California Baby sunblock - I kept a tube on her changing table at the beach house and then I had another tube in the beach bag. I also keep a small stick of it in my purse, even at home, just in case I need to put some more on while we're out and about.
2) Shade - even my water baby only wanted to play in the ocean for about 30 minutes at a time, but we were able to buy some more time in the sand by having a canopy set up to give us some shade. If you don't want to take an entire canopy (we had a service that set ours up for us), you can buy pop-up shade tents to help give the baby a break from the sun.
4. Play Mat - I decided to take one of Anna's play mats and I was really glad that I did. The play mat breaks down into squares and I was able to fit the entire mat into one of my reusable grocery bags, so it really didn't take up that much room in the car. The beach house had hard tile floors (no fun for little heads!), I had no idea what they used to clean them, and I also wanted to give her a central little spot to keep her toys and to play. The foam gave a bit of a cushion and it also gave her a spot that was easy to keep clean throughout the week. I was also really glad that I brought it because the home's pest control guy came while we were there, and he basically just sprays the pesticide all over the floor against the walls. It made me feel better that Anna wasn't crawling around on top of pesticide, and needless to say the mat got a good scrubbing when we got home.
5. Kiddo-friendly bug spray - the bugs actually weren't bad at the beach this year but it was still nice to have outside and down at the dock. I keep a bottle of the California Baby bug spray at the lake and I also have one that I keep in the jogging stroller for park purposes. I realized though that I forgot a bottle at the beach, so I bought a bottle of the only DEET-free stuff the grocery store had, which was the Cutter Family kind. I have also heard good things about Natrapel insect repellant, which is also DEET free. Regardless of what you get, just spray it on the stroller and the baby's clothes. That should be enough to keep the bugs away without having to spray it all over their skin.