They are the world’s most popular birth control product, but in Cuba, condoms are also ingeniously used to catch expensive ocean fish that they would not otherwise be able to reach.

In a country where the communist government is extremely paranoid about illegal emigration to the United States, and strictly controls who can own and use boats, “balloon fishing” has become a very cheap and effective way of catching fish like red snapper, barracuda and tarpon without having to leave the shore. The secret to this unusual fishing technique – latex condoms.

Fisherman along the Havana seawall use inflated condoms to create homemade floats that carry their lines as far as 900 feet into the ocean and keep the bait high in the water. As soon as they hit the surface of the water, the strong current starts pulling it out to sea, far beyond casting distance, and when a fish takes the bait, the line pulls free, and all fishermen have to do is reel it in.

It’s a very simplistic yet surprisingly effective fishing method that puts food on the table for hundreds of Cubans. “It’s amazing how strong they are,”Michel Perez, a young fisherman along Havana’s Malecon sea wall, praised the condoms.

Balloon fishing is so popular in Cuba that condom sales at Government-run pharmaceutical shops surge during peak fishing periods, like the snapper run. With just a few cents-worth of condoms, fishermen can build dozens of floats to catch fish worth $10 to $20 on Havana’s black market. In a country where the average monthly salary is around $25, that’s a pretty big deal.

Nobody knows exactly who invented Cuban “balloon fishing”, but the word among Havana’s fishermen is that someone saw a video of South Africans fishing using kites and was inspired to use inflated condoms instead. It turned out to be a stroke of genius that was soon adopted by a lot of amateur fishermen looking for an inexpensive way of boosting their income.

Before balloon fishing became a thing, Cubans practiced “cork fishing”, which implied going out into the ocean on inner tubes or blocks of industrial foam, but then the coast guard started cracking down on the practice, and they were forced to find an alternative. Condoms proved to be perfect for the job. They are cheaper and easier to make, and eliminate the risk of being caught by authorities and getting your gear confiscated.

Alex Romero, the 42-year-president of the state-backed Old Havana Federation of Fishermen, says that balloon fishing reflects “the ingenuity that Cubans always show in resolving problems without spending a lot of money.”