I love going indoor snorkeling in my landlocked state. It's only $125 and wildlife sightings are guaranteed.

• I'm a certified scuba diver who's lived in Colorado for five years.
• Strange as it sounds, I always recommend going snorkeling or scuba diving when visiting Denver.

It may seem strange to seek out an indoor, underwater activity in beautiful, landlocked Colorado, but hear me out.

The state — where I've lived for five years — is best known for its ski slopes and hiking trails. But I think one of the best things to do is snorkeling in the Denver Downtown Aquarium.

Although there are a handful of aquariums that offer scuba-diving experiences in the US, snorkeling and shark-cage experiences are much harder to come by.

The Downtown Denver Aquarium offers snorkeling with fish and rays for ages 6 and up ($125) and a shark-cage experience for ages 8 and up ($155).

These programs don't require any sort of diving certification, so I think they're a great underrated attraction for anyone visiting the state.

Marine-life sighting is guaranteed

When scuba diving or snorkeling in the wild, you never know what you're going to see — or if you'll see anything at all.

One big advantage of diving in an indoor tank is that there's no question you'll spot marine life, usually even some rare species.

In the Denver aquarium's shark tank, there's an elusive sawfish, a shark-sized fish with a long, toothed snout. Sawfish are critically endangered, so your chances of swimming with them anywhere else are low.

Plus, in the aquarium tank, you don't have to worry about harming a fragile coral reef as you dive or snorkel.

You become part of the tourist attraction

When you head behind the scenes at the aquarium, it's easy to forget that you're actually on display to all the guests.

During my shark-tank diving experience, it was an unexpected thrill to wave at young children gawking at me from the other side of the glass.

Since the experience comes with free admission to the aquarium, once you've finished up in the water, you can also observe fish, sharks, and rays from dry land — you might even spot another diver in a tank.

If you're already a certified diver, the experience is especially unique

If you're a certified scuba diver, the Denver Downtown Aquarium offers fish ($225) and shark ($235) diving experiences. There's even an Aquarium Ecology Specialty diver course ($495) if you're looking to get your certification.

Additionally, the building sits at 5,276 feet, which means it can be logged as an altitude dive — a unique opportunity for those used to diving below sea level.

I've done nearly 30 dives in different parts of the world, and my scuba experience in the Denver Downtown Aquarium shark tank was still one of the best.