During the Vietnam War the US dropped a lot more than just lead and bombs, they also left a lot of the fighter jet fuel tanks behind. During the war fighter jets could constantly fly all over Vietnam and the tactical jet planes relied on JP-8 fuel. This fuel was strapped on to the jet in external containers and when they would run out of fuel they would just drop them to lighten the weight of the plane. Because of that they pretty much littered Vietnam with the tanks.
The large fuel tanks were dumped onto the countryside by USAF jets so that they could maneuver better, protecting the pilots.
Those fuel tanks scattered throughout the country were eventually recovered and repurposed.
The citizens of Vietnam transformed them into makeshift canoes.
To our surprise, they seem to be perfectly suited for water travel.
Luckily these citizens were able to use the cast-off fuel tanks once the Vietnam war was over and they weren’t just littering their countryside.