Staying on the North Shore. Things I have planned to do.......body surfing everywhere, diving off cliffs into water wherever I can find them, and of course skydiving. Any other recommendations for an adventurous dude? Any fresh water holes or great trails you guys can recommend?
check out Waimea Falls Park in Waimea Bay. It's on the North Shore. It's a nature preserve with trails set aside, and a watering hole with a waterfall at the end. depending on what season it is, they open it up to swimmers and divers.
"I hear the surfin's choice." "It's nice to live on an island with no large cities." "GrrrrAAAArrrhgghhh!!!" ^ Name that movie (difficulty: easy)
Body surfing on the north shore in January is probably not a good idea if you don't live somewhere with really big waves. Head to Waikiki Haole.
Not adventurous stuff but go visit the Arizona Memorial at Pearl Harbor. FYI, it's free so if you pay someone to take you you are just paying for the ride. There is a WWII submarine museum next door where you can go through a sub which was kind of cool. That wasn't free... More stuff: Historicial Sites on Oahu Oahu Quick Guide
being adventurous is fun and great, but being alive is more important. when I was at the North Shore in November of '07, I saw the biggest waves my eyes have ever seen. they were over 20 feet high and even surfers were staying out of the water. pro surfers. they were telling people not even to put their feet or legs in the water... that being said, are you only staying on Oahu? you'll find plenty of surfing/bodysurfing/skydiving stuff on that island alone, but you got to get out to the Big Island, with the real cliff diving, the volcanoes, etc...
I've surfed alot on the North Shore, you better know what you are doing. Don't try it if the waves are over 8'- ask a local for wave size The best place to start might be Rocky Point, Log Cabins or Off the Wall, just ask someone Small Pipeline actually has good body surfing, but I recommend you stay away from Pipeline unless you are experienced with a body board and fins. And willing to risk your life. Sunset- can have a bad current but the inside might work depending on the size. Makapuu Beach Park on the eastern side of the island has some of the best body surfing in the world, and it might be breaking even though it is winter. Sandy Beach is good but probably won't have waves. Go to Surfline.com to check the waves prior to your trip and plan accordingly. There is some good fishing also, take a charter.