An inflatable is hooked to the back with a tow rope or harness. When you start picking up speed the inflatable moves slowly at first and then slowly raises above the water, picking up the pace, until it starts to hydroplane across the water. This offers a thrilling ride that can be compared to riding a roller coaster. Fast, fun, thrilling and a great way to spend the day.
There are towable tubes meant for one rider, or multiple riders, all the way up to a dozen. Some people prefer riding alone, but for a fun family bonding activity it can be great to ride together. They come in all different shapes, sizes, and styles to fit pretty much any personality. For instance you can get a typical round inflatable, for one or multiple people, or ride around the lake on a great big hot dog.
In fact, there is so much selection out there it can be hard to decide on one. You can really narrow down your options by looking at how many people you want it to hold and what price range you're interested in to save yourself some time while looking. As far as prices go there are ones for around a hundred dollars up to a few thousand, so being on a budget doesn't stop you from enjoying these. You'll find that the investment is worth it, too, because of the great number of uses you'll get out of it.
If you're hoping to have a the best summer out on your boat consider towable tubes as a great way to spend your days on the water.