The movement curve on the stage:[ The time-table  of the stage 4 ]

Stage 4. Lena
(EXPERT JUDGEMENT OF STAGE COMPLEXITY ON THE TEN-POINT SCALE = 4.0)
KACHUG (53 ° 57') - KIRENSK (57 ° 47')
Extension - 750 km
Locomotion - rafting

From Kachug village the expedition is in for the rafting along the largest river of Siberia - Lena (the length is 4400 km, the basin area is 2.490.000 sq.km). In the place of future travelling the river goes across Leno-Angarskoie plateau - hilly (up to 1000-1500 m), wooded land. Lena flows in a narrow incut valley. In the upper part of drifting to Zhigalovo (145 km) there are a lot of inhabited places, in the lower part the river goes along a relatively remote region up to the city of Ust-Kut. Next 265 km to Kirensk are more inhabited.
Kachug is the urban village (pop 9.400). It was founded in 1866. In the village shipbuilding yard and timber industry enterprise exist. There are ancient drawings near the village of Shishkin, the cave near the village of Zhitov, the cathedral in the village of Verkholensk.
Zhigalovo is an urban village (pop 6.000). It was founded in 1723. In the village small shipyard exists. In the neighbour village - Tutura the politician V.V.Kuibyshev had served his exile (the museum).
Ust-Kut is the city (pop 62.400). Ust-Kutskiy prison was founded in 1631. Today it is an important staging post. River workers call it the port of Osetrovo, railwaymen - Lena station.
Kirensk is the city (pop 16.200). It was founded for wintering in 1630 under the name Nikol'skiy Pogost, after - Kirenskiy Ostrog. In 1639 Erofei Khabarov had organised salt cooking here. The city centre is situated on the island, formed by Lena, Kirenga and its canal. Shipyard, woodworking enterprise and distillery exist there. There is also the museum of regional. Without any doubt the fourth stage is the simplest along all the travelling. What difficulties and perils can be mentioned? They are possible rains, mosquitoes and slow river. And may be also moving along the river transport facilities. In high water-time watercrafts go up to Kachug. But in 90s cargo transportations along Lena were so reduced that the danger to meet them is not so serious.
The rafting can prove to be very tiring: big distance, wide river, crosswind, slow current, the necessity of permanent rowing. All the mentioned are true also for the following raftings along Nizhnyaya Tunguska and Kotuy. For struggling against these circumstances one can use light outboard motor or around-the-clock rafting on the inflatable carrier with the dimension of 3-3.5 x 7-7.5 m (it is 1.5-2 times as much as the area of traditional catamaran), where it's possible to place a tent, an awning, to organise a fireplace.
From the other hand, the picturesque banks, average daily temperatures + 17-19 °C, beaches, abundance of fish (lenok, umber, dace, pike, perch), lack of blowing away by wind mosquitoes promise not so sad travelling.