Mind The gaps

When selecting a sky sometimes there will be parts of it that show through the gaps in the foreground, like underneath the pier here. selecting these areas by hand can be a pain, so instead try using the Magic Wand tool. in the tool options, uncheck contiguous. This means the tool will expand its search for similar pixels to include the entire image, not just the area you first click over. Hold shift and continue clicking until all the gaps are selected. Then switch to the Quick selection tool, hold alt, and paint over any parts of the selection you don’t want to include.