KASHIMA, SAGA PREFECTURE >> “Mud, mud, glorious mud,” I hum beneath my breath as my left leg disappears to the knee in the thick primordial ooze of the Kashima Mudflats in Saga Prefecture.

Part of the tidal zone of the Ariake Sea, at low tide the mudflats stretch unbroken from the town’s concrete flood defenses nearly 1,000 feet to the water beyond.

The muted gray expanse varies only in the presence of the not-yet-evaporated pools of sea water that reflect the sky above.

On this sunny afternoon, 40 of us are trudging through the mud to the start line of Kashima’s annual “Gatalympic” event, an assault course that stretches across the flats. The rules are simple: the first to reach the flag at the end wins.

Competition aside, the only problem is the mud. It has the same glutinous texture as mochi and sucks energy from the limbs with a dedicated proficiency.

At the start line, we are afforded scant few seconds to consider what lies ahead, but I am able to get a sense of the course’s five sections.

First, a “sprint” through the thickest of the mud.

Second, a series of polystyrene stepping stones, floating untethered atop the mud.

Third, paddleboards, ridden face-first, as if attempting to catch a wave.

Fourth, a path of planks, 82 feet of slippery wooden boards designed to depose; and finally: the tube, rising gently but treacherously to the podium.

“If I ever go to Japan,” I remember my 16-year-old self proclaiming to no one in particular, “I shall compete in ‘Takeshi’s Castle.’” Having arrived in the country to find the game show had ceased broadcast more than 20 years earlier, the Gatalympics might be the closest I’ll ever get.

And now, it is time.

The starting pistol fires, and my compatriots and I leap body-first into the mud to begin our assault. It is a competition, certainly, but there is a camaraderie in our opening gambit: It is us against the flats.

As I hit that first section, each step throws mud into my face, eyes, nose and mouth, and I am immediately covered. My breath runs ragged at the effort of tearing my legs out of the soupy quagmire, and I realize too late that I have underestimated the course.

I see fellow competitors come stuck at either side of me, trapped so firmly by the mud that their only release is a team of men who pull them out with thick safety ropes. My own temptation to give up is countered only by the idea of meeting the same embarrassing fate.

Eventually, the mud shallows and I board the stepping stones, making my way across them in fits and starts to the paddleboards.

Here, I regain my breath and, as I cross the soupy flats belly-down, I take an opportunity to look around at the carnage behind me. Everywhere, mud-covered competitors struggle forward as if they were in a third-rate comedy about the trenches.

“Utterly bizarre,” I think with a laugh, only for a thick, salty clump of mud to land in my mouth. Teeth now firmly gritted, I continue to the planks, where volunteers do everything in their power to make the slippy wood slipperier by adding more mud.

After everything, it is the final obstacle that proves to be my undoing: a mud-covered tube on an incline to the finishing flag, an off-white cloth flapping lazily in the breeze.

It seems obvious that the only way to reach the flag is to jump the tube entirely and land, triumphant, on the other side. I am mistaken: I jump, miss and, as my feet hit the tube, I come unstuck, rotate 180 degrees and land in mud so thick that I have to be dragged out.

From my undignified position, I see my nearest rival stride elegantly across the tube to claim the victor’s flag.

“Wasted effort,” thinks the competitive side of me. But the grin plastered across my face tells a different story.

The Kashima Gatalympics take place annually in late May or early June. Would-be competitors should sign up well in advance at gatalympic.com (Japanese only).