|Promo image of the deluxe Art & Arcana from Amazon|
"THE TOMB OF HORRORS"
The highest hill in the Egg of Coot
An island lying 100 miles east of Blackmoor
In the great desert west of the Wild Coast
On the border between the Paynim Kingdom and Perrunland
At the Eastern edge of the Duchy of Geoff
In a swamp somewhere in the Wild Coast
These suggested locations for the Tomb of Horrors come from the original version of the adventure — not the 1978 monochrome-colored module — but an even earlier iteration that was produced in 1975 for running as a tournament at Origins I in Baltimore, Maryland. This version is finally available as an extra included with the "special edition" of the new D&D art book Art & Arcana. You can see its cover in the promo image above; it's the small beige booklet featuring the original artwork by Tracy Lesch of the infamous Green Devil Face, which was later memorably rendered in color on the back of the 1981 reprint. Given its early date, it's a purely OD&D version of the tomb and is a great addition to the meager assortment of "TSR" adventures for OD&D.
These original suggested locations fit well with the "Great Kingdom" (early World of Greyhawk) map that I've discussed in previous posts such as Megarry's copy of the Great Kingdom Map, and suggest that Gygax may have been using this map for Greyhawk at the time. For reference, here is the map image —
On this map, the Egg of Coot lies in the center north, with hills in the northern region of the realm to possibly house "the highest hill". Blackmoor is to the south on the coast of the Great Bay, with plenty of space for an island "lying 100 miles east" in the bay, or depending on the scale, past the island kingdoms of the "Sea". To the west and southwest of Blackmoor, the Paynim Kingdom borders on Perrunland. Much further to the south lies the Duchy of Geoff, the eastern edge of which borders on the Kingdom of Faraz (not mentioned in the Tomb). Only the twice-mentioned Wild Coast is missing from this map, but the "great desert west of the Wild Coast" may be the Sea of Dust, suggesting the Wild Coast is to the south where the coast past of Keoland.
In the published version of Tomb of Horrors, the suggested locations were changed to:
The highest hill on the Plains of luz
An island (unmapped) In the Nyr Dyv
In the Bright Desert
At the western border of the Duchy of Geoff
Somewhere in the Vast Swamp south of Sundi
On an island beyond the realm of the Sea Barons
These revised locations correspond more closely to the published World of Greyhawk, although note that they were suggested in 1978, which was still several years before the World of Greyhawk Folio was first published in 1980.
The Egg of Coot was changed to "the Plain of Iuz"; Iuz occupies a somewhat similar north-central location in published Greyhawk and has "the Howling Hills" to the north.
The second entry, the island, was relocated to an unmapped island in Nyr Dyv, and second island was added "beyond the realms of the Sea Barons", which is closer in spirit to the island to the east of Blackmoor, particularly if the islands shown on the Great Kingdom map were an early version of the Sea Barons.
The desert was changed to "the Bright Desert", which on the published Greyhawk map is to to the east, rather than west, of the Wild Coast across the Woolly Bay. The "great" bit is dropped, presumably because the Bright Desert is much smaller than the Sea of Dust.
The eastern border of Geoff was changed to the western, presumably because that borders the great Crystalmist mountain range.
The swamp location was changed to "south of the Sundi", which means the Vast Swamp south of the County of Sunndi (member of the Iron League) on the Darlene map.
Finally, the suggestion of the border of Paynim/Perrenland was completely removed. In the Darlene map, the Plains of the Paynims no longer directly borders Perrenland; there are several new kingdoms between — Tusmit, Ket.
When the World of Greyhawk folio was finally published in 1980, the true location of the Tomb was finally revealed as being in the Vast Swamp:
There are many tales and legends concerning this area, but the most likely is that of the TOMB OF HORRORS (ADVANCED DUNGEONS & DRAONGS MODULE S1), the lost burial place of a lich who once ruled the morass and beyond into the cockscomb of Tilvanot. (a peninsula in the shape of a rooster's comb).
And then the expanded 1983 Word of Greyhawk boxed set further fixed the location as "probably" in "the heart of the Vast Swamp, in hex K2-97".