At a fairly long 7.5 km, this trail draws visitors with the remarkably clear water of Lake Spindžius, the Strėva sinkhole with a tavern said to have sunk to its bottom, the chance to walk through an ancient old-growth forest and other natural wonders. The trail is marked not with wooden signposts but with two dots of paint or arrows painted on tree trunks, so you need to pay attention, as these markings are not always easy to spot straight away. Walking time is about 4 hours. The Spindžius forest is said to be one of the most beautiful and valuable forests in the park, encircled by the Strėva river and lakes. The forest really is beautiful – lush and green, with many pines surrounded at their feet by huge patches of bilberry bushes, like a green carpet dotted with blue. This is no ordinary forest: in many places it is old-growth woodland. Old-growth forests are characterised by very old trees, and here as many as four generations of trees of different species and ages grow side by side. From an information board on the riverbank we learned that the name of the Strėva river is thought to come from the Sanskrit word sravati – to flow, to stream. Folklore stresses the river's sacred nature, because it flows out "towards the rising sun". Flowing eastwards, the river turns out to link as many as 20 of the park's lakes. The marshy Strėva, overgrown with slender young trees, reeds and other wetland plants, led us to Lake Spindžius. It is the largest lake in the Spindžius Landscape Reserve, covering 106.7 ha. Spindžius is one of Lithuania's green lakes: thanks to the algae living in it, the water takes on a bright green tint in sunlight, although at times it is completely clear. The deepest point of the lake is 24.5 m. Much of the lakeshore was steep and sandy, laced with the roots of mighty trees, which served us as steps down to the remarkably clean and clear water. Finally, the Green Trail brings you to a unique spot where the Strėva river links two lakes, with a bridge across the stream. When you come out onto the asphalt road, turn right; after a few hundred metres along it you will find signs pointing to the Drabužininkai barrows. After about 2.5 km on a gravel road winding through the forest, you will reach the last highlight of the Green Trail – the Strėva sinkhole. It is a bowl-shaped hollow 20 metres deep, often called the sister of the Devil's Pit. This sinkhole is wrapped in legends; one of them tells of a cursed tavern that stood here and sank into the ground, where devils used to revel. One fast day the devils held a wedding. As soon as the rooster crowed, the tavern sank with all the devils in it. Local people say that mysterious sounds can sometimes still be heard here. In reality, about 18,000 years ago, during complex processes of glaciation and glacial retreat, sediments buried a broken-off block of ice. When it melted, this steep-sided hollow was formed.