if i had to pick ONE favorite attraction from our honeymoon in hawaii, it would definitely be the nakalele blowhole. located on maui's most northern point, the lava rock has been cut away by the pounding surf over the years and it formed a hole. every time a wave comes in, the water shoots through the hole like a geyser. the water coming out of the blowhole can reach as high as 70-100 feet in the air! several books/sites warn not to get too close, but uh, we didn't listen.
it felt like one of the amusement park log rides where you know you are going to get soaked and you just wait for it and wait for it... then WHAM. it's really loud but sooooo much fun! we were like little kids at a waterpark. definitely a must-do.