Lilla Karlsö is a small Swedish island in the Baltic Sea, situated about 3 km (1.9 mi) off the west coast of Gotland and 4.5 km (2.8 mi) from Stora Karlsö; it is part of Eksta socken. During summer there are tour boats from Djupvik 15 km (9.3 mi) south of Klintehamn.

The island has an area of about 1.6 km² (0.62 sq mi) and is 66 m (217 ft) high. Most of the island consists of a limestone plateau. Parts of the shoreline are bordered by steep cliffs. The island is mostly covered by alvar. There are several caves and up to 16 m (52 ft) high limestone pillars.

Since 1954, the island has been owned by the Swedish Society for Nature Conservation and it is now a nature reserve. It is mostly known for its rich flora and birdlife. There is some old broadleaf forest, which is unique for Gotland, and several rare plants for Sweden such as Lactuca quercina (called 'Karlsösallat' in Swedish), hart's-tongue fern and Petrorhagia prolifera. There are also colonies of several thousand pairs of guillemots and razorbills. Along with neighbouring Stora Karlsö, the island has been designated an Important Bird Area (IBA) by BirdLife International.^[1]

• Stora Karlsö
• Gotland

• Official website

57°18′40″N 18°03′40″E / 57.31111°N 18.06111°E / 57.31111; 18.06111