Zac Sunderland is no ordinary 16-year-old boy. While his friends play video games and go on their first dates, the high school sophomore is traveling around the world -- on a sailboat, no less.
"I'm 100 percent sure that I'll be able to do this," Zac told ABCNEWS.com of his yearlong trip that began on June 14, which he hopes will make him the youngest solo American sailor to circumnavigate the world.
"It's going to be an amazing adventure," Zac told "Good Morning America." "Life changes you as you move along through it."
But so far, Zac's amazing adventure is taking him for a ride. One recent entry in his online blog points to exhaustion.
"I've been feeling anxious about the situation and about the boat," Zac wrote. "I'm tired and I'm tired of rocking around going nowhere. The weather should go back to normal by the end of the week, but that seems unbearable at the moment!!"
"I can hear in his voice that he's really tired," said his mother, Marianne Sunderland, who recently spoke to Zac via satellite phone. "The name of the sailing game is patience. ... We've just been encouraging him that that's part of the whole thing."
Zac is a veteran of the seas despite his young age. He was basically raised on a boat -- Zac's first home was his parents' 55-foot yacht -- and he sailed for the first time at just 6 weeks old. His father is a master shipwright near their home in Thousand Oaks, Calif.
Sunderland told ABCNEWS.com that she's not worried about her son's safety.
"I know that he'll have rough times, but I'm not worried because the boat is in good shape and he's got a lot of good equipment, a lot of experience and a lot of support," Sunderland said.
"The end result is that he's going to experience a huge range of emotion and experience and struggles and successes that are going to make him into an incredible man," said Sunderland on "Good Morning America."
The dangers of Zac's trip are numerous. Circling the globe is an ordeal of at least 21,000 miles that has cost some intreprid sailors their lives. There are sudden storms, waves of 20 feet to 60 feet, even pirates to contend with. Cape Horn, the route around South America, has some of the world's most treacherous waters.
Then there's the thousands of hours of isolation, coupled with sleep deprivation during stormy seas when the boat must be constantly tended, which can have profound psychological effects on some people. Collisions with submerged objects and the danger of being swept overboard are constant perils.
All this is leading some to ask whether the Sunderland's are letting their son take too big a risk.
Teenagers often don't yet have the brain power to weigh the consequences of big decisions such as Sunderland's, Dr. Elisabeth Guthrie, a pediatrician and psychiatrist at New York's Columbia University told ABCNEWS.com.
"Teenagers are still in the midst of a dynamic period in their brain development, and their ability to make decisions," said Guthrie, who has not treated Sunderland. "In general, teenagers are nowhere near as mature in their decision-making abilities as adults."
"Teenagers do, in general, believe that they're much more immortal than they actually are, so they're not necessarily good at assessing how a particular risk may pertain to them."
When asked if he's thought about the potential for death on his journey, Zac told ABCNEWS.com that he tries not to.