Hidden Lake is a lake on the Kenai Peninsula of Alaska, formed by an ancient channel of the Kenai River. It is located entirely inside the Kenai National Wildlife Refuge. The lake is deepest at its southeast end, with depths up to 148 feet (45 m). The back country section of the lake in the northwest has several islands and depths in the range of 10–70 feet (3.0–21.3 m). Being in the foothills of the Kenai Mountains, much of the shoreline is very steep, and wooded with birch and spruce trees. The only outflow from the lake is Hidden Creek, a short, shallow creek that flows into the Kenai River just North of Skilak Lake.