This is mildly strenuous for the twins, but fun enough that they are out here every second they get, climbing into the willow via the two avenues open to them, or swinging on the boat float. In our last house we had a giant cherry tree (a seriously overgrown behemoth at least 80' high) that we attached a couple of floats with ropes to as swings. It was a miracle none of them ever flew off because they sure went high on those swings (leaving me with flashbacks to a cousin who fell out of a tree, required a metal head plate, and was never again the same). The kids were all rather sad when we moved here and found we hadn't any trees of note in the yard. I had some good intentions to build a tree fort last summer, but finances being what they were the floats continued to languish, then the other day I came across the rope ladder in a DIY store and couldn't help but buy it. Richard went a step further and made some limb steps for the tree itself.
My original plan included a platform and one of those long plastic slides off the end. We'll see how far we get this summer!