CRATER LAKE — National park officials have temporarily closed Crater Lake to scuba diving over the threat of invasive species.

CRATER LAKE — National park officials have temporarily closed Crater Lake to scuba diving over the threat of invasive species.

Park officials announced Wednesday that the closure will remain in effect while they develop rules to be sure that microscopic species, such as quagga mussels, spiny water fleas and viruses, don't hitchhike into the pristine lake waters on diving gear.

Park Superintendent Craig Ackerman says the lake is becoming more popular with divers, raising the threat that some new creature could invade the lake ecosystem and change it forever.

Lying in the caldera created by the collapse of a huge volcano more than 7,000 years ago, Crater Lake is the nation's deepest and clearest lake. It holds the world record for water clarity — 140 to 142 feet of visibility straight down, Ackerman said.

Though only about 10 people a year dive in the lake, it is becoming more popular, park officials said. The September issue of Travel + Leisure magazine listed Crater Lake as the nation's top lake scuba diving destination, despite the fact divers have to carry their gear down a long steep trail to reach the water.