There is "layering', and there is "air-layering." Now perhaps, water-layering?
Traditional layering occurs in nature, and it has been used for thousands of years to propagate figs. A shallow trench is dug below a low branch, which is bent down into the trench, weighted with rocks or logs, and soil, and the outer leafy tip of the branch is left uncovered, sticking up. Several months later, the part of the branch near the tree is cut loose, the weights are removed, and the now-well-rooted branch is dug up and moved to a new place.