The Ho-o-maniya blowhole is sometimes spectacular and other times a fizzle. During the southwest monsoon (June is the best time), high seas can force water 23m up through a natural chimney in the rocks and then up to 18m in the air. At other times the blowhole will leave you limp. From the parking area, it's a 300m up-and-down walk past numerous vendors and, sadly, lots of rubbish.
Driving, look for the 1km-long access road about 6km northeast of Dikwella, just west of the 186km post.