I've been to LC dozens of times over the past 25 years, and it gets better every time.
We started going to Lake Compounce before the water park was installed, when it it was basically a couple of rides, a train, and a sandy beach. I recently brought my nephew there after not having been in a couple of years. The transformation into a first class (if petite) park has been amazing.
The water park is expanded every year with more slides & attractions, keeping masses of people cool in the hot summer sun. There are areas just for babies and toddlers, as well. If you want to cool off without using the water park, there are two rides that will get you just a bit wet - the Sawmill Plunge log flume and the Thunder Rapids gentle water raft. Both are suitable for kids of most ages (height restrictions apply and are indicated at the park entrance and at each ride).
Don't miss riding the Wildcat (a traditional wood coaster) and the Boulder Dash, a unique wooden coaster that hugs the treed mountainside. For a great view of the surrounding area, take a 30 minute ride on the Sky Ride. This is basically a ski lift, and I would not recommend the Sky Ride for people afraid of heights or parents with slippery young kids. There is nothing but the bar in front of you, and you are high above the rocks. On a hot sunny day be sure you're hydrated and sunscreened before you get on.
Locals' secret - go to the park on Sunday. On summer weekdays the park is packed with busloads of summer camp kids. If you think you'll attend more than once, buy a season's pass and come late in the day. Camps usually clear out by 4pm and the lines for rides thin out. A season pass costs roughly the same as two single tickets, and passholders get three free bring-a-friend passes as well as discounts on food and merchandise.
There are several places to eat at Lake Compounce, from carnival snacks to sit-down restaurants. Soda is free and available at locations all over the park.
The midway games are not my thing, but it seems everyone wins something. In true midway fashion, the prizes are worth about what you pay to play.
In October this family-friendly park turns into the Haunted Graveyard. The water park and kiddy rides are closed, but all of the major rides are open as well as creepy Halloween themed attractions.
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