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Tell Gemini. :)

A **400-foot (approx. 120 to 125 meters) drop** in global sea levels corresponds to the climatic conditions of the **Last Glacial Maximum (LGM)** roughly 21,000 years ago. During this period, massive volumes of Earth’s water were locked up in continental ice sheets, exposing nearly **27 million square kilometers** of shallow continental shelves.

This newly exposed terrain—roughly equivalent to the combined landmass of North America and Europe—fundamentally transformed global geography. Here is a breakdown of what became accessible on foot or via short canoe hops:

### 1. Major Continental Land Bridges (Fully Walkable)

* **Beringia (Asia to North America):** A massive land bridge hundreds of miles wide emerged between Siberia and Alaska. Humans and megafauna walked freely between the Eurasian and North American continents.
* **Doggerland (Europe and the British Isles):** Great Britain and Ireland were entirely landlocked extensions of mainland Europe. You could walk on foot from modern-day France, Belgium, or the Netherlands straight across the dry bed of the North Sea to London and beyond.
* **Sundaland (Southeast Asia):** The shallow waters of the South China Sea disappeared, fusing the Malay Peninsula, Sumatra, Java, Borneo, and Bali into a massive southern extension of the Asian continent.

### 2. Expanded Megacontinents & Basin Dry-Outs

* **Sahul (Australia, New Guinea, and Tasmania):** While Australia and Asia remained separated by deep-water oceanic trenches (the Wallace Line), Australia, New Guinea, and Tasmania were joined into a single giant continent called Sahul.
* **The Persian Gulf Basin:** The entire Persian Gulf was a dry, fertile river valley. The Tigris and Euphrates rivers flowed together through the basin before emptying into the Indian Ocean far to the south.
* **The Mediterranean and Black Sea:** While the deep Mediterranean basin retained its major seas, many island groups were connected or dramatically expanded (e.g., the Italian peninsula stretched much further, and the Adriatic Sea was largely a flat plain).

### 3. Coastal Expansions (Short Canoe or Walking Access)

* **North America’s Coasts:** The Atlantic and Gulf of Mexico continental shelves dried out. Florida more than doubled in physical surface area, and the coastlines of the Eastern Seaboard shifted outward by tens of miles.
* **East Asia:** The Yellow Sea and East China Sea floors were exposed plains, connecting the Korean Peninsula directly to mainland China.

### Summary of Impact

In total, a 400-foot drop opened up vast travel corridors across the globe. While deep oceanic trenches (such as those separating Sundaland from Sahul) still required maritime travel, an ancient traveler could have walked continuously from the tip of South Africa, through Europe and Britain, across Asia into Alaska, and all the way down to the depths of modern-day Indonesia without ever needing a ship.