The Atlantic coastline of Palm Beach County is about in length. It consists mainly of barrier islands and peninsulas, including Jupiter Island, Singer Island, and Palm Beach Island. These islands are separated from the mainland by the Intracoastal Waterway, with much of the waterway locally known as the Lake Worth Lagoon. The main barrier landmasses are split by four inlets: the Jupiter Inlet, the Lake Worth Inlet, the South Lake Worth Inlet, and the Boca Raton Inlet. Two of the four inlets are natural, but significantly altered – the Jupiter and Boca Raton inlets – while the Lake Worth and South Lake Worth inlets are man-made, with the former dug in the 1890s and the latter created between 1926 and 1927. Several other islands exist within the Intracoastal Waterway, including Hypoluxo Island, Munyon Island, and Peanut Island.