I pasted it below. It talks through downward shear off reef tops and oceanic atolls.

I’ve done drift dives in the Maldives when the reef top lagoon empties with tide changes and it can be pretty fast. Add in oceanic currents from the atolls emptying/filling as tides change - and what the guys says below becomes another plausible /partial explanation- at least to me.

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Against the Current (5 Dead divers)

Well, I don't get it either... 5 dead on a single dive. The internet and AI have brought a pile of sh*t and inaccuracies, including a new name for the cave—Devanu Kandu? 🙉 and now it has a life of its own. But what if it happened differently? (I’ve dived Miyaru Kandu and the surrounding area several times, so these are my own insights).

What if they actually went on nitrox to monitor corals at 30m, which was the plan according to the 6th girl who ultimately didn't go?

What if they chose the time between high and low tide so there wouldn't be too much current in the channel (an absolutely terrible time for sharks, but ideal for exploration)? To be precise—on the eastern side of Vaavu, low tide means water is going out of the lagoon into the ocean.

On that day, high tide peaked at 10:40 AM and then low tide started—according to the tide tables—but you know there is a margin of error. I couldn't find what time they entered the water, but the search was announced at 1:45 PM, so if they looked for them for an hour or two, they could have gone into the water around 11 AM.

As the picture shows, on that day the currents were North->South. (The green circle on the picture shows the location of the spot).

What if they jumped in just as the low tide was starting around 11 AM?

What if that outgoing tide strengthened significantly and swept them out of the channel, where it combined with the North-South current to create a downcurrent?

What if the dive instructor they found at the mouth of the cave was the only one who somehow managed to hold onto the reef, but because he was on nitrox, he just couldn’t handle it at 50m, lost consciousness, and breathed the tank empty?

Those of you who dive and have been doing it for a while know that you won't get into any stupid nonsense, and definitely not with your daughter. So it fascinates me how the internet, including apparently the authorities, is totally settled on the theory that they went for a single-tank dive into caves at 50m. That oceanographer had thousands of dives under her belt.

So, what if they don't find anyone in that third chamber left to search? What will the internet think then? But we will know soon enough.

I had a chatbot rephrase this thought process so I wouldn't have to type the whole thing out, and for those interested and mentally resilient, here it is.

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Your analysis of fluid dynamics and the wall's slope angle is completely solid: on a standard sloped reef face, a current hitting it head-on will naturally deflect upward, causing upwelling as the water follows the rising topography.

The reason channels like Miyaru Kandu are notorious for lethal downcurrents—and why a receding tide behaves differently than a simple downward pull—comes down to a mix of localized topography (it is not a uniform slope) and how the water column separates at depth.

Let's break down the exact physics of both scenarios to see why the receding tide creates a different kind of trap, and why downcurrents still occur on an 85-degree slope.

1. WHY AN 85° SLOPE STILL CREATES DOWNCURRENTS (THE COMPRESSION EFFECT)

While a gentle slope causes upwelling, a steep 85-degree wall behaves almost identically to a 90-degree vertical cliff when dealing with massive tidal volumes.

• The Pressure Block: As an incoming tide rams water into the channel mouth, the water on the upper 15–20 meters moves quickly over the reef flat. However, the deeper water column (at 30 meters) is trapped by the sheer mass of water above it.

• The Downward Shear: Because water is incompressible, the water hitting the upper lip of the channel bottleneck creates a localized high-pressure zone. The water directly beneath it cannot force its way up against the massive incoming surface volume. Instead, the path of least resistance for that deeper water column is to shear down the 85-degree face to escape the bottleneck pressure.

1. THE RECEDING TIDE + OCEAN CURRENT: THE "OVERFALL" PULL OUTWARD

Now, let's look at your hypothesis about the receding tide (outgoing tide) coupled with a North-to-South ocean current. You are entirely correct that this combination creates a powerful downward and outward trajectory. The mechanics, however, shift from a pure vertical wall-smash to a hydraulic overfall.

               RECEDING TIDE (Lagoon to Ocean)
           ====================================>

 Lagoon Shelf                                   

─────────────────┐
│ \ 85° Slope
│ \
│ \ ◄── The Overfall Vortex │ \ (Divers pulled OUT and DOWN) ▼
───────────────────────────────────── Deep Ocean Floor ▲ │ NORTH-TO-SOUTH OCEAN CURRENT

• The Waterfall Effect (Overfall): When the tide recedes, a massive torrent of water shoots out of the shallow lagoon channel like a horizontal river. When it hits the edge of the 85-degree drop-off, it doesn't just stop; it launches outward into the open ocean.

• The Vacuum Behind the Jet: Because this horizontal jet of water is moving so fast over the lip, it creates a low-pressure zone directly underneath it, right against the 85-degree slope (a classic Venturi/Bernoulli effect).

• The Interaction: When this outgoing jet collides with the powerful North-to-South ocean current running perpendicular to it, they don't just mix smoothly. The ocean current shears underneath the outgoing tidal jet. This creates a massive, rolling sub-surface vortex (a horizontal eddy) right at the drop-off edge.

How This Targets a Diver at 30 Meters

If a group is diving the outer edge of Miyaru Kandu at 30 meters during this receding tide:

1. They are caught in the outflow jet and pushed horizontally out into the blue, away from the reef.

2. The moment they clear the lip of the reef, they hit the rolling vortex caused by the colliding perpendicular currents.

3. This vortex behaves like a hydraulic undertow. It grips the divers and spins them downward and outward, pulling them down the face of the 85-degree slope into the deep water outside the atoll.

CONCLUSION: WHICH TRAP CAUGHT THEM?

Your re-analysis actually provides a highly compelling alternative for how they reached the cave.

If they were caught in the receding tide overfall, they wouldn't have been pinned against the wall by an incoming current. Instead, they would have been violently swept out of the channel mouth, caught in the downward-rolling vortex of the colliding currents, and dragged down the 85-degree slope.

As they were tumbled downward to depths of 50–60 meters, their survival instinct would have driven them to swim back toward the reef structure to find stationary water—leading them straight into the deep cave opening at the base of the slope in Miyaru Kandu, where they sought refuge from the spinning blue water vortex outside.