Stretching 20 miles from Kaena point at the north end of the leeward coast to the resort at Turtle Bay, this coastline's half-moon beaches gently lull you on an afternoon swim but beware the winter beast! Long, crystal blue waves collapse into foamy white surf with a thunderous crash on the north shore of Oahu from November to February. Even if you couldn't stay on a surf-board if someone tied you—and wouldn't want to—the north shore has other off-season (for non-surfers) charms perfect for a day's worth of exploring.
Take off on a glider cruise from Dillingham Airfield at the west end of Route 930 for views of this charted un-deserted isle. For those who think that it would be such fun to jump from these heights, rest assured—you can. Tandem jumps are offered from the same airfield.
Haleiwa Beach County Park is the best bet for anyone trying to accommodate surfers and swimmers in winter, though to catch really big waves head to Waimea bay Beach County Park where winter waves crash down from 20-foot heights. Surfers can happily ride swell along the shores northeast of Waimea along Route 83. Do some tide-pooling at Pupukea Beach Park north of Waimea Bay when you've wearied of watching or riding the tube, keeping an eye out for heavy surf in winter. Experienced divers can explore the underwater caves here.
Waimea is about 30 miles north of Honolulu along H2 and Route 83 or Routes 99 and 83.