From Kerry Sanders, NBC News correspondent

Ecotourism has exploded in the last five years, and Belize couldn’t be sitting prettier. The United Nations World Tourism Organization estimates ecotourism is a $60 billion dollar-a-year business. And because Belize is late to the huge business of tourism, in many ways, this country is still untouched.

That’s turned out to be fortunate. Much of what tourists do when they visit this Central American country is to get up close to Mother Nature. Forty-two percent of Belize is a green zone, a protected territory by government decree.

The most popular activities are scuba-diving and snorkeling. But there's much more to see and do, like tubing on rivers that flow through mile-long caves. Native Maya Indians believed these were the opening to the underworld. Zip-lining through the jungle is another highly-energizing thrill.

Our NBC crew didn’t want to quit.

But there are growing fears here in Belize that too many tourists will become too much of a good thing. I met Eugine Batpist, a 30-something Belize native. His worldview of the problem is borne of extensive travel and from the time he lived in the U.S. He says, “We need to learn from Jamaica, Cancun, the Bahamas and Florida. Our goal is keep what we have here now. Not to become commercial. To keep the feel of nature. To keep what the Mayas knew.”

But already there are signs ecotourism is giving way to those commercial pressures. Jungles that had been accessible only by mountain bike, are now open to four wheel ATVs.

And lush land is slowing being cleared for new hotels and time-shares. The development questions now faced in Belize are not new. What experts warn is, in the long run, it costs more to try to re-grow what was here, than to leave untouched in the first place.

The world’s largest landscape architectural team, EDSA, from Ft. Lauderdale, Fla., says one of the biggest problems is the lack of a definition. No one can say exactly what “eco-tourism” is.  And while organizations are trying to define that term, often business interests move that line in the interest of making money.

Experts advise that if tourists want to know if the trip they’re planning is indeed eco-friendly, they should ask questions: How many visitors come to this spot each year? How often are the locations taken out of use to give Mother Nature a break? How do they define eco-tourism?