MIAMI — Tito Gauenzi waved his arm across a party tent tricked out like an oceanfront nightclub. “Miami and polo don’t get any sexier than this,” said Mr. Gauenzi, the chief executive and founder of the Beach Polo World Cup in Miami.

The noonday sun sparkling off the ocean turned the lounge seating a blinding-hot version of white. The tent floorboards rumbled from the thumping D.J. booth and hooves galloping on the beach mere inches in front of the structure.

A caviar-loaded tray from a server arrived for a group on the couches, their champagne bucket dripping from 80-degree heat. Tapas and liquor stations were laid out for attendees who bought three-day, $650 V.I.P. tickets to watch polo from inside the tent.

“No bikinis in here unless they are covered — the dress code is sexy chic,” Mr. Gauenzi said as two young women in bikinis click-clacked by, covered in netting with holes large enough for a dolphin to jump through. Barefoot beachgoers lined the edge of the playing field, marveling at polo riders speeding in packs.

It was one of the biggest polo weekends of the year in the United States. The Beach Polo World Cup, held April 20 to 23rd in Miami Beach, is an official, competitive tournament that is also designed to promote the sport. About two hours away in Wellington, Fla., riders battled it out in the finals of the U.S. Open Polo Championship, one of the most prestigious polo tournaments in North America.

Polo’s quirky handicap system enables amateurs and professionals, of all genders and ages, to compete alongside each other at the highest levels of play. Off the field, rivalries blur quickly because hired players often switch teams during the season. And the organic camaraderie creates a sideline party scene people take as seriously as the sport.

Nacho Figueras, the champion Argentine polo player and former Ralph Lauren model, walked into the oceanside tent on Miami Beach, unhassled by fans.

“For us, the horses are not just what we get on to play polo, but you know, it’s our lifestyle,” said Mr. Figueras, who breeds and trains more than 350 ponies. “There’s a lot of connection to that thing that is underneath me that goes beyond an animal with four legs.”

Polo has often been called the “sport of kings,” and it can cost millions of dollars to move players and ponies all over the world. Polo team owners, also known as patrons, often pay for the breeding and training of 200 to 500 ponies at a time. Professional polo players are usually hired for matches or the whole season.

Polo ponies gallop up to 30 miles per hour in quick bursts on grass fields the area of nine football fields, so players bring about dozen horses per match to prevent exhaustion and injury. Riders nimbly change ponies on the sidelines in seconds by swooping from one saddle to another in a graceful arc.

Melissa Ganzi, an avid player in her mid-50s, was resting in the players’ tent next to the field, along with a few other players zipping up boots and wiping sweat. Ms. Ganzi, a partner in the Miami event, is the founder of the World Polo League and owns private polo clubs in Aspen, Colo., and Wellington with her husband, Marc. (In Aspen, they play polo in the snow.)

Only one element of the sport scares her: “It is people who can’t ride,” she said, referring to less experienced players. “I know how dangerous it could be.”

Another world existed in Wellington, where the crowd was as boisterous as the South Beach tent but more patrician. On one side of the field, attendees had rented private tents with cocktails and sushi and sandwiches. On the other, the members of the private Polo Club at the National Polo Center drank rosé and Kentucky whiskey and sampled from a buffet with a caviar and blini station. The dress code was sports coat and sundress, with a few hats that seemed as large as U.F.O.s.

The tables were filled with players, families and patrons who own enormous polo enterprises.

“We are highly competitive,” said Daniel K. Walker, the chief executive of F&M Bank in California, and a respected polo patron who owns about 50 ponies that he and his sons use. (He referred to the cost of running a polo enterprise as his “money pit of choice.”)

Mr. Walker was visiting a table with a raucous Argentine group. “All of these friends are my worst enemies on the day I play against them,” he said. “And when the game is over, you’re the best of friends.”

At halftime of the finals championship match during the traditional “divot stomp,” when spectators try to even out the field by stepping on displaced mud and grass — usually with a drink in hand — it started pouring rain.

But the deluge seemed to invigorate the partying plutocrats gathered under tents. One patron wondered, sincerely, why no one thought to hire two helicopters to dry the field by hovering back and forth.

A rainy hour later, the final was officially postponed, but many guests lingered.

There was no customary stampede for the parking lot, which was a good thing because valets were struggling with a few Bentleys and Alfa Romeos stuck in the mud.