HANOI, July 3 -- A private mini-submarine made by a Vietnamese mechanic went on its first sea trial on Sunday, local media reported.

At around 8:00 a.m. local time on Sunday (01:00 GMT), the mini-submarine started undergoing its first sea trial in Vietnam's northeastern waters. The submarine was escorted by Vietnamese naval ship, reported local Tien Phong (Pioneer) online newspaper.

An evaluation council of Vietnam's Ministry of Defense (MoD) will carry out quality evaluation while the submarine is continuously diving and floating for hours.

Nguyen Quoc Hoa, the one who performed the mini-submarine production, said on Tien Phong that prior to the sea trial, his product must pass around ten times of trial in pools and then in lakes. It also passed two-day exams of floating, diving, running in circles, moving backwards and handling collisions while diving hosted by the MoD.

Hoa, a director of an engineering company in Vietnam's northern Thai Binh province, some 110 km southeast from capital Hanoi, started to produce a mini-submarine in 2014.

One year later, Hoa and his engineers studied to produce a second mini submarine, which is supposed to be in smaller size and have more functions than the first one.

According to Hoa's design, the submarine is made of steel and weighs about nine tons. It is able to operate at a maximum depth of 50 meters at a maximum speed of 15 nautical miles per hour. It can dive for three days and three nights with two people on board.