The Yerevanian lake is an artificial water reservoir in Hradzan canyon which itself has been inhabited since time immemorial. In 1968 excavations revealed obsidian tools in the Paleolithic cave on the right bank of the lake which belonged to hunters living inside it. Its hard to say what else was going in the cave as only 1/3 of it has been explored. Due to the fact that the water level increased, it became impossible to dig further, so the lake keeps hiding many secrets, and I guess that its secrecy level has increased, for the cave has remained within the confines of the US embassy.
Anyway, the lake has more stories to tell. In 1976, a trolleybus with 96 passengers lost control, fell into the lake and sank to its bottom Luckily, Shavarsh Karapetyan, who was a ten-time fin-swimming World Record-breaker, was then running along the lake. He dived to the crushed trolleybus which was lying at a depth of 10 meters and rescued 20 people. Shavarsh was then 23 year old, yet he had to stop his sports career because he ended up with pneumonia & blood contamination. Nowadays, such a story would instantly go viral, but since the USSR could not accept having such accidents, news about it was banned. The story of heroism was published in the ’80s, after which our hero received 60,000 letters, according to Wikipedia. Later, he was awarded a UNESCO “Fair Play” award for his heroism.
As you can see, the secrets of the lake are deeper than the lake itself.