Lanikai Pillbox Hike

This short but steep Oahu hike is basically a 30-minute stair-stepper workout with an insane payoff — panoramic views of turquoise Lanikai Beach and the twin Mokulua Islands from old WWII bunkers. Don't let the dramatic warning signs at the trailhead psych you out (one reviewer jokes it reads like a helicopter rescue is already warming up). The trail on Kaelepulu Drive in Kailua gets crowded, especially at sunrise, but those views of the Windward Coast are absolutely worth sharing the space. Bring water since there's zero shade, and wear shoes with good grip — the trail gets slippery when wet.