Simple enough achievement but you'll need to progress a bit in the game to do it. You'll need to purchase the Blacksmith and the Training Dummy from the castle skill tree to add them to the docks.
As well as that, you'll need to find the Pizza Girl. She's in the second area, Axis Mundi, which is always to the east of the first area. Once you engage her services she'll also appear at the docks.
Once you have all these at the docks, you'll notice several items you can spinkick (LB) off. There's the chimney on the Blacksmith's hut, a lamp nearby, targets all around the Training Dummy (and the Dummy itself), and then across to the chimney of the house with Pizza Girl outside, and the sign in front of it. I thought you might have to land in Charon's boat to finish this, but it popped for me in midair after hitting the last one.