The idea of building a tunnel to Sakhalin was proposed back in the late 19th century, but due to economic impracticality and lack of funds, it was never realized. Surveys on the construction of the tunnel were carried out in 1929–1930. In 1950, Stalin proposed the idea of connecting Sakhalin to the mainland by railway. Options considered included a ferry crossing, a bridge, and a tunnel. Soon, at the official level (a secret decree of the USSR Council of Ministers dated May 5, 1950), a decision was made to build a tunnel and a backup sea ferry. Like the Transpolar Mainline, the tunnel was most likely intended for military purposes — to supply Soviet Army units stationed on Sakhalin. The construction of the tunnel crossing was assigned to the USSR Ministry of Internal Affairs (railway branches) and the USSR Ministry of Railways (tunnel works, transferred to the Ministry of Internal Affairs in 1952).

The technical specifications for designing the tunnel and adjacent railways were approved by the USSR Council of Ministers on September 6, 1950. To speed up construction, the route was planned to be built using a simplified (effectively temporary) scheme; for example, at the initial stages, the use of untreated sleepers was allowed. Detailed engineering and geological surveys in the area of the proposed tunnel construction were not conducted.

On Sakhalin, the length of the railway line from Pobedino station to Cape Pogibi (the start of the tunnel) was to be 327 km. The axis of the tunnel under the Tatar Strait began at the Pogibi siding; 23 kilometers from there was Vangi station, from which a branch was planned southwest to Cape Uangi, where a berth for a sea railway ferry was being built. In total, nine railway stations were planned on the island section of the mainline. The length of the tunnel itself from Cape Pogibi on Sakhalin to Cape Lazarev on the mainland was to be about 10 km (the narrowest section of the strait was chosen), its route passed north of the ferry crossing. On the mainland, it was planned to build a branch from Cape Lazarev to Selikhin station on the Komsomolsk-on-Amur — Sovetskaya Gavan section, with a branch to a temporary ferry crossing. The construction of a traction power station near Lake Kizi was planned. Completion of construction with the organization of a temporary ferry crossing was scheduled for the end of 1953, and the tunnel was planned to be put into operation by the end of 1955. The total freight turnover of the designed line in its first years of operation was expected to be 4 million tons per year.

The construction of railway branches to the tunnel was mainly carried out by released GULAG prisoners. By agreement with the USSR Prosecutor's Office and with the permission of the Council of Ministers, the Ministry of Internal Affairs released up to 8,000 people from correctional labor camps and colonies, sending them to the Ministry of Railways until the end of their sentences. Exceptions were persons convicted of banditry, robbery, intentional murder, repeat thieves, those sentenced to penal labor, prisoners of special Ministry of Internal Affairs camps, for whom the Ministry's permission did not apply. On Sakhalin, this was Construction 506 (Tymovskoye settlement), on the mainland — Construction 507 (De-Kastri settlement). By early 1953, the total number of railway builders on both sides of the strait was over 27,000 people. Construction, especially on Sakhalin, was carried out under conditions of practically complete lack of infrastructure and shortage of equipment; due to the emergency nature of the work, living conditions in the camps for prisoners were unsatisfactory even by GULAG standards.

Preparation for tunnel construction on the mainland was carried out by conditionally early-released, hired specialists, and military personnel (Construction 6 of the Ministry of Railways). In February 1953, Construction 6 was also assigned to build the power station near Lake Kizi. By spring 1953, the number of builders was 3,700 people.

After Stalin's death and the mass amnesty of prisoners, work on the entire project was curtailed. According to the recollections of one of the young engineers, Koshelev (a recent graduate of MIIT in 1951, assigned to this construction, who led the construction of the first shaft to the tunnel axis), the situation was as follows: "In December 1951, I graduated from MIIT. I was sent to work at Construction No. 6 of the Ministry of Railways on Sakhalin Island... The workforce was difficult. The majority were early-released prisoners. They were also paid wages depending on output, but strictly on time. The only difference from those who came here freely was that they had to sign a non-departure agreement. At our site, out of five foremen, three were early-released... I was appointed foreman of the main works. I was given twelve brigades under my command. We were tasked with constructing a shaft on the seashore with a diameter of eight and a half meters and a depth of about eighty. And when we finished, it was proposed to make crosscuts and start tunneling. We finished tunneling the first shaft in February 1953..."

In spring 1953, Stalin died. And some time later, the construction was closed. Not suspended or mothballed, but closed. Yesterday we were still working, and today they said: "That's it, no more." We never started tunneling. Although everything was ready for this work: materials, equipment, machinery, and good qualified specialists and workers. Many claim that the tunnel was doomed by the amnesty following Stalin's funeral — there was practically no one left to continue construction. This is not true. Of our eight thousand early-released, no more than two hundred left. The rest waited for eight months for an order to resume construction. We wrote to Moscow about this, asked and begged. I consider the cessation of tunnel construction a wild, absurd mistake. After all, billions of rubles of public money and years of desperate labor were invested in the tunnel. And most importantly — the tunnel is truly necessary for the country..."

On the mainland, 120 km of broad-gauge railway track was built along the right bank of the Amur River from Selikhin station to Chyorny Mys station (the road was later used for timber hauling). In the area of the planned ferry crossing, embankments were built (their remains are still visible), and preparatory work for the construction of piers was carried out. At Cape Lazarev, from where the tunnel was to be laid, a shaft was dug, and 1.6 km from the shore, an artificial island 90 m in diameter was built. On Sakhalin, work was carried out under worse conditions, and not a single kilometer of railway was built. The preparatory work on the route (earthworks, clearings, etc.) allowed the construction of a dirt road Nysh — Pogibi, which was used in Soviet times for timber hauling.

Since 1973, Sakhalin has been connected to the mainland by the Vanino — Kholmsk ferry crossing.

The idea of building a tunnel crossing through the Tatar Strait outlived the Soviet Union. Similar proposals were made in 1992 by the head of the Sakhalin Railway, A. B. Vasilyev. In 1999, Minister of Railways Nikolay Aksyonenko announced the need to develop a project to connect Sakhalin's railway network with the mainland; in 2000, representatives of design organizations conducted a terrain survey. Implementation did not begin.

The project to connect Sakhalin Island with the mainland by permanent railway communication involves laying rails from Selikhin station, located on the Baikal-Amur Mainline near the city of Komsomolsk-on-Amur, to Nysh station on Sakhalin Island. The total length of the railway line is 582 kilometers. The crossing from the mainland to Sakhalin has three construction options: a tunnel under the strait 12.4 kilometers long, an embankment 16 kilometers long with a shipping channel, and a bridge crossing 6.6 kilometers long.

Sources:

https://dic.academic.ru/dic.nsf/ruwiki/345772