We just happened to hear from other travelers about this local blowhole and decided to set out and look for it.
First of all, drive north on high 30, Honoapi'ilani Highway. It's a beautiful drive.
You will see a bunch of cars parked near mile marker 38 on the left side of the road, this is where the trail starts that leads down to the blowhole. The trail is pretty a steep and vertical. I would recommend wearing good shoes, not flip flops, wear sunscreen and a hat if your sensitive to the sun. Lastly, bring plenty of water!
At the beginning of the trail there is a sign warning not to get too close to the blowhole because it can cause death. I believe a man from Calif died in 2011 from being sucked into the hole from it's strong force.
At the end of the hike down the hill, take a look off to the right and look for the heart rock. It's a great place to take pictures with a spectacular view!
I do have to say that we went during low tide and didn't see much. If you want to see the "great show" I would recommend going during high tide. Just stay back from the hole.