Mistakes are easily made and it’s often too late to rectify the situation by the time someone notices. That was the case with Spain’s supposedly state-of-the-art submarine the S-81 Isaac Peral. The submarine was commissioned in 2013 as one of four new submarines for the Spanish Navy, but there’s just one problem with its modern design. Once it’s submerged the S-81 Isaac Peral may never be able to resurface again.

This is because a miraculously unnoticed flaw in its design means that the ship is around 75 to 100 tons overweight. Which means Spain essentially invested in a submarine which can only move in one direction--down. The mistake is said to be the result of a pesky decimal point placed in the wrong place during calculations. And it’s a single dot which can cost an extra $9.7 million per meter of the hull, which has to be extended to regain its balance.

Considering $680 million has already been invested in this single ship as part of a total $3 billion for all four subs, this is hardly a (mistake) which can be brushed under the rug. It took an additional seven years to repair and the submarine finally joined the Spanish fleet in May 2021.

You can view the clip here (8 min 52 sec – 10 min 03 sec).