Aloha,
Kalahari.

Turn the Hawaiian chain upside down, carry it half a world, and it comes down across northern Botswana from the Namibian border to the edge of the Makgadikgadi. Oʻahu lands in Ghanzi district: Honolulu’s antipode is 33 km from Dekar, and central Oʻahu’s, around Wahiawā, just outside it. Kauaʻi lands near Charles Hill, by the Namibian border. Maui lands towards Sehithwa, by Lake Ngami. The Big Island, the largest twin, fills the country between Maun and Gweta: Kailua-Kona faces the bush south of Maun, Hilo lands 61 km from Gweta.

Botswana’s towns sit just off the twins, so from them the sandwich is deli or sloppy rather than exact. Ghanzi is a deli sandwich, 16 km short of Oʻahu’s north shore; Maun, the gateway to the Okavango, is 59 km short. Gaborone misses by 469 km, and Johannesburg by 729 km: from the big cities of southern Africa, the nearest exact spot is in northern Botswana.

Every Hawaiian town above 5,000 people and every county seat. On the other side, every town in Botswana and Namibia above 5,000 and every district capital, and the cities of South Africa, Zambia, Zimbabwe and Angola whose other slice lands off Hawaii, each listed if it lands within 300 km of land or is a capital or a city of a million. Exact means land opposite land at the town’s own point; where the other slice would get wet, the table gives the nearest spot from which an exact sandwich is possible.

No Hawaiian town has a town within a kilometre of its antipode: the Kalahari twins are bush, farms and villages too small for GeoNames’ list. Every Hawaiian town is still exact, so the sandwich is made by driving to the right spot on the Botswana side.

A sandwich’s elevation bonus is the height of one end plus the height of the other (Sandwich Law § 1.4). The Board scores it the way the map shows it: from the average height of the ground over cells about 20 km across, so every spot in a cell scores the same and you only need to be in the right cell, not on the summit. These are the corridor’s best cells, one per area, each with dry land at both ends.

1. +3,840 m29 km from Volcano (Hawaii)cell average 2,920 m108 km from Gweta (Central)cell average 920 m
2. +2,240 m6 km from Kēōkea (Hawaii)cell average 1,240 m85 km from Maun (North-West)cell average 1,000 m
3. +1,840 m13 km from Wailua Homesteads (Hawaii)cell average 600 m46 km from Charles Hill (Ghanzi)cell average 1,240 m
4. +1,600 m9 km from Waimea (Hawaii)cell average 680 m93 km from Maun (North-West)cell average 920 m
5. +1,440 m4 km from Schofield Barracks (Hawaii)cell average 280 m5 km from Dekar (Ghanzi)cell average 1,160 m

The Big Island does the work: the best cell, on the slopes above Volcano, averages 2,920 m, and its twin in the Kalahari near Gweta 920 m. The Kalahari itself is a high plateau, which is why even the Botswana ends add close to a kilometre.

The window. Both slices must go down within five minutes of the same UTC instant (Sandwich Law § 2.1). The sandwich lobby holds you to it: when the first slice lands, the other side has five minutes.

The clocks. Hawaii keeps UTC−10 and Botswana and Namibia UTC+2, and none of them change their clocks: Gaborone is always exactly 12 hours ahead of Honolulu. Noon in Hawaii is midnight in the Kalahari.

The light. Two exactly opposite points are never in daylight together: sunrise at one end is sunset at the other. The atmosphere bends a little sunlight over the horizon, so twice a day, on a clear flat horizon, the sun is up at both ends at once for about seven to eight minutes. Put the bread down then and both photographs get golden light, one at dusk and one at dawn.

The seasons. Opposite, though Hawaii barely notices. The Kalahari summer, from about November to March, is hot and brings the rain; its winter nights can be cold.

The geometry is the easy part; the hard part is a person at the other end, and the site does not match strangers. English is spoken on both sides, which helps. The Botswana end is best reached from Ghanzi and Maun, both of which have lodges, guides and people who know the tracks.

Then open an attempt in the sandwich lobby. It gives you a code and a link to send through whatever channel you already share, shows both slices when they arrive, and runs the five-minute window. Much of the Kalahari side is farmland, communal land or protected area, so ask before you walk in, and carry water. The exact grade allows a kilometre of slack, which is usually enough to find somewhere you are allowed to stand.

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