TAMPA - It's bound to be a muggy, steamy and oppressive evening on Friday - perfect weather for runners taking a stab at the Picnic Island Adventure Run.
The 400-plus runners will be celebrating the 10th anniversary of a summertime series that's become a quirky local racing tradition. The 3.6-mile slog through bay waters, serpentine hills, soft sand and obstacles has become a badge of honor for some, an entertaining workout for others.
"I thought I'd give it a shot and, four years later, I'm still doing it," said Florida Gulf Coast University student Jimmy Patterson, 20. The recreational runner says the event is about more than speed. You have to think about avoiding slips and falls.
"You know what to expect, but it's always different," Patterson said. "The course is different, the water is different."
Co-founder Jim Hartnett said the first run at the South Tampa park, in 2003, offered a diversion for runners with few local race choices in the summer. Since the beginning, runners have faced an off-road route filled with simple yet infuriating obstacles: hurdles, tires, logs, even cargo nets tied to the base of the Picnic Island playground swingset.
The water challenge, a quick dip into Tampa Bay, makes the race more "tolerable." It's a fun experience, but no cake walk, he said.
"They may be caught off-guard by how tough it is," said Hartnett, race director and owner of TampaRaces.com, which hosts a dozen local off-road races and series each year.
The Picnic Island series - held one night in May, one in June and one in July - first attracted about 150 participants, and it's grown to as many as 800 a night, Hartnett said. Now the race has reached a happy balance, with 400 and 500 runners at a time, about half of whom are recreational runners.
"It's such a fun time. Everybody really does have a smile on their face," Hartnett said of the races, which always end with a pasta dinner and party at the park pavilion. "It's rewarding."
Jon Docs, 50, has run and volunteered at the Picnic Island races for about six years. An ultradistance runner more accustomed to 50-kilometer and 50-mile events, he said the adventure run makes him focus more on his strength. The water run can be brutal.
When the tide is high, "It's just too hard to run. You can't really swim, either," Docs said. "When it gets up to your knees, it really slows you down."
Hartnett said his experience in adventure racing helped with the design of the Picnic Island race. But while adventure races usually include kayaking and cycling, this event always has focused on the running.
He didn't realize it would be part of a nationwide surge in adventure runs. Commercial road races featuring hazardous obstacles are all the rage, many featuring turbo marketing campaigns to complement their extreme names: Tough Mudder, Savage Race, Warrior Dash.
Running USA estimated as many as 1 million people participated in these kinds of off-road obstacle races in 2012, an enormous increase in a category that registered little more than a "blip" a decade ago.
Hartnett said he loves the increase in local adventure run offerings. "Man, I wish they were around when I ran," he said. There is one key difference between these races and Picnic Island. Many of the larger events require team participation. Picnic Island racers are tracked solo.
But there's also something nice about the less-threatening Picnic Island series when compared to the more extreme events or ultradistance races, Hartnett said. People can come once "and put a notch in their racing belt" and know they've done something special.
"Not everybody can do a marathon or a 50-mile run," he said. "But everyone can walk or run 3.6 miles."
For more information about the Picnic Island Adventure Race on Friday, visit www.tamparaces.com