Rawa Pening

Rawa Pening is a shallow natural lake of around twenty-five square kilometres in a basin between Merbabu, Telomoyo and Ungaran, dammed in the colonial period for irrigation and power and now averaging only a few metres deep. It is a working lake: fishermen use bamboo lift-net platforms and small boats, and floating cages raise fish. Its central problem is eutrophication - nutrient runoff has produced water hyacinth cover across a large part of the surface, which is cleared repeatedly and returns, choking the water and reducing the open area year by year; the weed is now harvested for handicraft as one response. The setting under the volcanoes at dawn, with mist and the lift-net frames silhouetted, is what draws photographers. Ambarawa's railway museum is a few minutes away.

History

The name means "clear swamp", from the Javanese bening. The lake is thought to have formed between 18,000 and 13,500 BC after a period of heavier rain; it reached its largest size from 11,000 to 9,000 BC and then shrank to its present size by around 6,000 BC (Wikipedia, Lake Rawa Pening).

What's there

• Bamboo lift-net platforms - the fishing frames standing out of the shallow water.
• Water hyacinth cover - the weed choking large parts of the surface.
• Volcanoes around the basin - Merbabu, Telomoyo and Ungaran above the lake.
• Dawn mist - the reason photographers come, with the nets silhouetted.

When to go

May to September; dawn for the mist. Half a day.

Good to know

The hyacinth problem is severe and parts of the lake are effectively unnavigable. Water quality is poor. Boat prices are negotiated. It is a working lake, not a leisure one.

Nearby

Ambarawa and its railway museum are north; Salatiga is east.

Key facts