The introduction of the first tin dredger in 1907 allowed the tin mining industry on Phuket to expand into a vast new area that had previously been untouched. Several types of dredges were used locally. Hydraulic dredges sucked the ocean floor for the alluvial deposits of tin through a pipe, separated the tin and discharged the spoil on the shore through a floating pipeline. Elevator dredges employed an endless chain of small buckets to scrape the ocean floor and separate the tin ore from the rest of the spoil, which was discarded back into the ocean. The coastline of Phuket and the surrounding ocean floor have been dramatically altered by dredging for tin.