The primary reasons people swim in the summer are to cool off, relax and have fun. Pool toys help you relax and have fun. After you dive in the water and get cooled off, what next? You could go lay out and read a book, or not. It's a lot more fun to get out your pool toys.
There are pool games for large groups and also for small groups.
Pool volleyball or pool basketball are the most fun for large groups. If you have a wide variety of ages (ie grandparents with grandkids) you should definitely go with volleyball.
Works best with those of similar age and athletically inclined. It is a difficult game to play if you can not swim or jump very well.
Remote Control Toys:
A remote control sailboat or fish are the most popular. These toys can be fun in small groups or alone. If you get a remote control sailboat, you can also take it to the lake.
Fins and snorkel can enhance swimming. Other diving toys are pirate coins and sunken treasure (there are many styles to choose from). When I was a kid we used to take the lid off an old mason jar to live for.
Relaxation Pool Toys
A foam lounge is very popular. It has more stability than inflatable lounges. There is a remote lounge that has a joystick to move around in the water.
Coolers make is so you do not have to go into the house a lot. You can put your floating cooler in the pool with you and use your remote lounge to get yourself drinks.
There is a waterproof case that floats your ipod and speakers. In addition, you may consider some wireless outdoor speakers that are shaped like landscaping.
The mainstay pool toys are inflatable arm bands (for children), noodles and inflatable rings.