Pristine beaches with cool waves, silky sands and beautiful bodies serve as the location. And with just a ball and a net, anyone can enjoy the game.

No doubt, beach volleyball is widely viewed as a "party sport", played among friends during relaxed recreational outings.

Yet, to the teams representing Singapore at the South-east Asian Beach Volleyball Championships at Sentosa's Palawan Beach from Thursday to Saturday, the sport is a strenuous test that places a premium on skills and fitness.

"I struggled with muscle aches initially, there are different kinds of muscles that I have to engage, in the thighs especially," said men's national player Gilbert Tan.

"I got the muscle aches just by running on sand. Normally when you step on sand and apply pressure, your leg will sink into the sand. There's weight on your ankle and it's harder to lift up your legs."

Compared to indoor volleyball, which has six players on each team, beach volleyball fields only two players. A match can last for an hour, and its short but explosive rallies of about 10 seconds each places a high demand on stamina.

"For indoor volleyball, you might not even touch the ball once for a whole rotation. If you're in the corner, you're practically not in the game," said national beach volleyball player Mark Shen, 21.

"For beach volleyball, a team of two has three touches, so each one has to touch the ball every rally.

"You have to be alert all the time and chase after every single ball. It's much more tiring."

Shen, trained by national coach Dean Martin, undergoes a gruelling training routine to maximise his overall speed. He first has to sprint towards the court's baseline, before charging back towards the net in an attempt to hit the ball across the court to a specific spot.

Moreover, no substitutions are allowed - which means the players have to persevere through exhaustion or even injury, otherwise the team will have to forfeit the contest.

Yet, for Shen's 21-year-old team-mate Poon Pei Jie, the tactical side of the game is enough reason to participate in the sport.

"It's about how you're going to move your opponent around. It's a lot of gameplay and strategy involved, so I like those aspects," said Poon, who made the switch from indoor volleyball in 2015.

"Instead of mindlessly hitting the ball over, we're actually looking at the opponent and what's the next course of action we can take to score a point."

Beach volleyball made its Olympic debut at the 1996 Atlanta Games, but the scene in Singapore is much younger. While it has been widely played since the 2000s, it was only in 2015 when national senior and youth teams were formed.

Nevertheless, Poon believes the scene is picking up. He said: "I'd say the local competitive scene has been growing, especially this year, from the start of the year to now.

"There are more competitions and more people are exposed to beach volleyball."

This week's biennial event will be the first one hosted by Singapore, who will be sending three men's and three women's teams to challenge regional powerhouses like Indonesia and defending champions Thailand.

Shen and Poon are gunning for a medal at the tournament.

Said Shen: "It's our first international competition together... We got nothing to lose."