The group of 11 hikers was sloshing through knee-deep, muddy water on the Florida Trail south of U.S. 41 when an elderly lady announced, almost casually, “Snake.”

The six at the front of the single-file line didn’t hear her, but everyone behind her did and stopped.

There, to the left of the trail next to a dwarf cypress, lay a brownish-black serpent with its fierce-looking head in the full, upright and locked position. It was not coiled to strike, but its countenance did not indicate happiness.

Big Cypress National Preserve ranger Melissa Hennerman stepped forward to identify the suspect.

“A water moccasin,” Hennerman said calmly. “Let’s step wide to the right and go around it.”

The water moccasin, otherwise known as the cottonmouth, is one of only six species of venomous snakes found in Florida. If a hiker were to be bitten here — about two miles from the nearest road — it would likely be a while before Miami-Dade Fire Rescue’s “Venom One” response unit could ride to the rescue.

But no one panicked. The hikers kept wary eyes on the snake — which fortunately stayed put — gave it a wide berth, and continued down the trail. When they caught up with the leaders, conducted by ranger Isobel Kalafarski, it turned out her group had walked right by without seeing it.

After a brief break to sip water, the entire group continued deeper into the cypress forest. No one mentioned heading for home.

The hikers were on a special ranger-led trek of about seven miles round-trip to reach Robert’s Lake Strand for the purpose of viewing a small stand of really tall cypress trees. The strand lies roughly halfway between U.S. 41 (Tamiami Trail) and the Loop Road terminus of the Florida Trail, which winds all the way up to the Panhandle. The “Hike to the Big Trees” is conducted only three times during the winter and is not for the faint of heart or weak of knees.

Hikers must be in pretty good shape for this long walk, which goes on rain or shine, hot or cold. Long pants, long sleeves, plenty of water and snacks, and rugged closed-toed running shoes or hiking boots are required — along with, most importantly, a stout walking stick, which the rangers handed out at the Oasis Visitor Center before the start of the hike.

The trail is nearly always knee-deep or higher in water, except in the driest of droughts, and is made of mud, broken limestone, cypress knees, and random roots. Its unevenness and unexpected deadfalls have been known to make trained fitness enthusiasts weep. Those who traverse it are constantly lurching around in a near tumble, saved only by their trusty wooden staffs.

Traveling slowly is beneficial for two reasons: you are less likely to break your ankle and you are more likely to spot wildflowers, such as the delicate violet petals of Glades lobelia, yellow blossoms of bladderwort, and colorful swamp daisies. And if you are trudging fast, you are almost guaranteed to miss orchids — such as the cow horn, butterfly and dingy star — peeping from the cypress boughs. These delicate plants which grow on trees are akin to lottery winners, Hennerman said, because they thrive only with the perfect mix of moisture, fungus, temperature and other key environmental factors.

Even walking fast, it is nearly impossible to miss the pineapple-like bromeliads dotting the tree trunks. They are seemingly everywhere at every height. But if your splashing footfalls are too loud, you’ll miss the Big Cypress soundtrack — the calls of red-shouldered hawks, pileated woodpeckers, ospreys and the softer tweets of songbirds.

The group took about four hours to reach a small hammock in the middle of a slough surrounded by ferns and cocoplums with enough dry ground for a sit-down picnic lunch. Beside the tiny island, a six-foot alligator lay on the bottom of the slough motionless, but its eyes were open. It never moved — nor blinked — while the hikers ate lunch.

Afterward, the group shouldered their day packs and waded waist-deep through Robert’s Lake Strand to the “big trees,” which stood hundreds of feet tall on wide trunks the size of tool sheds. Somehow these giant cypress had escaped South Florida’s logging boom, which felled most of their neighbors from the 1920s through the ’50s.

“Maybe they were just too hard to get to,” suggested ranger Jonathan Riner.

That comment drew a hearty, knowing laugh from the hikers.