Thinking of Visiting the World’s Tallest Tree? Think Again.

For hundreds of years, a tree known as Hyperion has stood quietly among its fellow giants deep within Redwoods National and State Park in Northern California. Inaccessible by trails, Hyperion, a coast redwood, can be reached only by bushwhacking through heavy vegetation and crossing a river.

Still, a flood of travel bloggers, tree enthusiasts and recreational climbers has managed to do so — and has damaged the surrounding undergrowth in the process. As a result, the National Park Service has closed off access to Hyperion, which, at 379.1 feet tall, is the world’s tallest living tree.

Now, under a rule adopted this year, anyone who gets too close could face up to six months in jail and a $5,000 fine.

“I hope people understand that we’re doing this because our eye is focused on protection of resources and safety of the visitors,” said Leonel Arguello, the park’s resource manager.

Mr. Arguello said the Park Service’s decision to establish the rule limiting access to the tree had come after an increase in people forging their own trails and climbing the tree. Large amounts of garbage and human waste had also been found in the area.

Under the rule, which took effect in March but received widespread attention after SFGATE wrote about it over the weekend, people will be prohibited from getting within a square mile of the tree, Mr. Arguello said. The Park Service will regularly send out rangers to patrol the area, he noted.

The tree’s remote location makes it difficult for emergency medical services to access, Mr. Arguello said. “I hope people understand that we’re doing this because our eye is focused on protection of resources and safety of the visitors,” he said.

Mr. Arguello said no one had been arrested or fined yet. He added that while $5,000 was the maximum fine under the rule, park rangers would likely initially ask trespassers to leave the area or issue a $150 ticket.

Redwood trees are among the tallest and oldest trees on Earth, and their existence dates back to the Jurassic period some 200 million years ago. Hyperion was discovered in 2006 by two naturalists and confirmed by Stephen Sillett, a redwood expert.

There is a certain irony to Hyperion’s popularity, observers say.

Despite its “champion height,” it is not worth the trek, according to Mr. Arguello: From close up, you can see only the first 150 feet from the ground. Above that, only the bottom of branches are visible.

“It’s the most unimpressive tree you’ll ever see,” he said. “I’ve worked at this park for 33 years now, I’ve seen most of the old growth in this park, and this particular tree is not that impressive at the base. It’s just really tall.”

He added: “When you can’t see the top 150 feet of tree, it doesn’t really matter how tall it is.”

But the mystery of what stands above that bottom 150 feet is in part what draws some visitors.

Young redwoods have a conical shape, said William Russell, a professor of environmental studies at San Jose State University. But as they get older, the trunks mature into a cylindrical shape with thick branches toward the canopy making them “really appealing to climbers,” Mr. Russell said.

Climbing any of the park’s trees for anything other than research is prohibited. But Mr. Russell said he had been hearing about recreational climbing in Redwood National Park for a number of years. Illicit climbing is “really problematic” for the tree and its surroundings, Mr. Russell said, but “climbers are the least of it.” Climate change and commercial logging remain perpetual pressures on the fragile system, Mr. Russell said.

Redwoods require moisture from coastal fog to keep their canopies damp. “The more coastal fog you have, the better off you are as a coastal redwood,” Mr. Russell said. The tops of trees like Hyperion are fragile ecosystems, Mr. Russell said: The crowns are more drought-stressed and also rich with entire mini-forests of vascular plants and nests of marbled murrelets, an endangered seabird.

Lucy Kerhoulas, an associate professor of forest physiology at California State Polytechnic University, Humboldt, described monument trees like redwoods, spruces and Douglas firs as competing in “an arms race for light.” But the microsite of a particular tree — its soil composition, species and site location — can make all the difference in its height. Hyperion is near a creek and on a protected north-facing slope.

Ms. Kerhoulas has noticed an increase in “loving the trees to death” when it comes redwoods, but for hikers hoping to see a “glamourous, tall, jaw-dropping” tree, she said the Jedediah Smith Redwoods State Park was “a much better use of time and energy.”