Wow--what a cool place! The Lost River Caverns in Hellertown are an absolute must -- this underground world is full of mystery and natural beauty. You get to walk through paved, well-lit pathways inside a limestone cavern where an underground river flows, and the constant temperature of about 52 degrees Fahrenheit adds to the atmosphere. The guided tour is fun and educational, with knowledgeable guides pointing out the geology, flowstone formations, and historic tidbits (the place has been open to the public since the early 1930s). It's a great outing for families, couples, or anyone looking to do something unique -- you'll be under the earth's surface and totally immersed in nature's work. The gift shop and picnic area across the road add to the charm. Highly recommend to add this to your route if you're in the Lehigh Valley area -- you won't regret discovering this hidden gem. read more