Dumme mosse, Nature reserve near Jönköping, Sweden

Dumme mosse is a bog in northwestern Småland, west of Jönköping, crossed by Riksväg 40. Most of it formed through waterlogging of solid ground, and its peat is mainly little-decomposed Sphagnum peat, 4–6 metres deep in the central parts. It is drained chiefly by the Dummeån and partly by the Dunkehallaån, and boardwalks let visitors walk across it.

The southern part of Dumme mosse became a nature reserve in the late 1960s. In 1998 the reserve was enlarged to 2,865 hectares, taking in most of the bog plus the neighbouring Ulvakullamossen and Store mosse mires. The main road across the bog was laid out by Danish forces during their attack on Jönköping in 1567.

The name Dumme mosse refers to the bog itself, which is crossed by Riksväg 40, the road whose predecessor the Danes laid across the wetland in 1567. Visitors today follow boardwalks laid over the peat, and the reserve is managed by Länsstyrelsen i Jönköpings län, the county administrative board.

Dumme mosse is crossed by Riksväg 40, which divides the bog, so plan your route to avoid crossing the road on foot. Boardwalks laid over the wet peat let walkers get into the central parts without sinking; stay on them, since the peat there is 4–6 m deep. The reserve lies about 225 m above sea level in northwestern Småland, west of Jönköping.

The bog's peat is mostly little-decomposed Sphagnum peat, and its central parts are 4–6 metres deep. Most of Dumme mosse formed when solid ground became waterlogged rather than as a lake filling in, which is why the reserve covers such a broad, flat expanse.