Deep Lake is a 66-acre (27 ha) body of water lying eight miles (13 km) south of Olympia in Thurston County, Washington. It is 17 feet (5.2 m) deep at its deepest point and has a water volume of 771 acre-feet (951,000 m3). The lake drains into Black River by way of Beaver Creek and Scott Lake. Deep Lake is located in Section 3, Township 16N, Range 2W, Willamette. The lake is bordered on two sides by Millersylvania State Park. An RV resort camp occupies the lake's eastern shore. The lake's fish population includes stocked rainbow trout and naturally reproducing largemouth bass, bluegill, yellow perch, and pumpkinseed.