Welcome to the border between the US and Mexico. Home to numerous migrant deaths every year, snarling police officers – and the most subversive game of volleyball in the world.

Known affectionately as "wallyball", the border sport is thought to have been first played as part of a Mexican fiesta in 1979, before being re-staged by a magazine editor in 2006.

And the cheers of the beach crowds are no small political message, reducing a 2,200 mile border with the highest number of legal and illegal crossings in the world to a mere playing net.

"For us, it represents the celebration of the union of two countries," Jose Lorenzo Villegas, the mayor of Naco in Mexico, told Reuters at a game in 2014.

The cheers of the beach crowds are no small political message (Reuters)

It must be one of the only games played by different nations where both teams get to play on home turf, he added.

"What's unusual is that both the Mexican and U.S. teams are playing at home, with the fence as the net," he said, confirming the game is not exactly illegal.

Since then, wallyball has gained fame and is now an annual April tradition in Naco, Arizona and Naco, Sonora Mexico. Other games take place between Tijuana in Mexico and San Diego in California.

Yet the fence presents its own difficulties, being too high for "spike" hits and needing lobs of 50ft or more - often resulting in bruises on the hands and wrists of players.

Undettered however, the game lends a whole new spin to US presidential candidate Donald Trump's claim that he would build an unbroken wall and "make the Mexicans pay for it".