The reasons for Kaleva's fate remain unknown to this day. On June 14, 1940, the plane was traveling between Tallinn and Helsinki when it was shot down. It then sunk to the bottom of the sea along with two crew members and seven passengers, some of whom were foreign diplomats.

After Estonia regained its independence, the search for the wreck took off both in Finland and Estonia. Kaido Peremehe, manager of the diving company Tuukritööde OÜ, has participated in the search since the early 2000s. "We did the current study purely as a hobby. We finally managed to put the finishing touches to the story, but the previous studies were a great help," he said.

Many others attempted to find the plane over the decades and help was provided by the Estonian Navy and a U.S. research vessel as well.

According to Peremees, the wreck remained unfound for two simple reasons.

First, the sea bed is very uneven and rocky around the area in question. It was almost impossible to differentiate the pieces of the plane from normal rocks. In the meantime, however, sonar technology and the software used to process the signal were advancing rapidly. The tools, which had previously been designed for purely military applications, were gradually reaching the level of commercial users.

"For some time, we tried to find another seaplane OH-ALI that went missing northeast of the Tallinn shoal. When we saw these small pieces of the aircraft, we understood that we have the technical capability to start from scratch in the Kaleva areas. The photos taken at the time were good for that time but did not have sufficient resolution to separate man-made objects from natural with 100 percent accuracy," Peremees said.

When they returned to the search area, they were able to see the wing of the plane, an engine and the undercarriage with the wheel, recognizable at a depth of between 71 and 76 meters on the seabed, he said.

The deep diver says that, remarkably, the wreck site matched the original testimonies given at the time of its downing.

For example, the head of the Keri Island naval post confirmed the crash north of the island in a report sent to a senior naval officer, a document found by Peremees in the state archives in 1993. Another witness from the Keri post confirmed the testimony and it can also be found in Risto Niku's book "Kaleva surmalend". The diver says a description by Ilmar Juutilainen, who was a Finnish fighter ace who went to identify the scene of Kaleva's wreck, corresponds with that estimate too.

The downing of the plane was witnessed by a Soviet submarine also. Estonian fishermen, who also saw the attack, went to check out the site. The submarine then surfaced and confiscated the passengers' valuables, allegedly including a bag containing diplomatic mail.

In recent years, the number of ship and plane wrecks found in the Baltic Sea has increased significantly. Among others, the Transport Administration has given a helping hand, and its findings, Peremees said, have provided better context to help find the Kaleva.

"The Transport Administration found a similar type of plane around Abruka and there have been others reported around Harilaid. When you look at the size of the wrecks, we can estimate what the Kaleva wreckage might be like. It seems that many pieces have been removed," the diver told ERR. "It is too soon to say anything conclusive, of course, but some items and parts could have been removed as early as in the 1940's or during the years 1956-1957."

Peremees also wanted to specially highlight the assistance of Avo Jüris, who handled the search for many years.

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