Character Analysis
Lance is an archetypal carefree California druggie surfer dude, trapped in the hellhole of the Vietnam War. His surfing prowess is part of the reason Kilgore agrees to escort Willard and company to the mouth of the river.
He's not really a major character—more just a colorful sideshow. We see Lance surf, drop acid, and feel right at home with the mountain tribe's animal sacrifice ceremony. He also playfully throws out a smoke grenade, which swathes the river in smoke and contributes to Mr. Clean's death. Along with Willard, he's the only crewmember who actually manages to survive the mission, maybe because he's too high all the time to be afraid. Actor Sam Bottoms admitted to being high or tripping during much of the shooting for real. ("We were bad boys," he remarked (source).)
The trip upriver is its own hallucinogenic nightmare, so Lance's altered states of consciousness hardly even register as all that different from real life.
It's all groovy.