Chole Bay sits on the eastern shore of Mafia Island, a relatively remote island in the Tanzanian archipelago roughly 120 kilometers south of Dar es Salaam, and has long served as a natural anchorage along Indian Ocean trade routes. The bay's sheltered waters and proximity to the open ocean made it a practical stopping point for seafarers across many centuries, and the surrounding seabed is believed to hold evidence of that long maritime history in the form of ancient shipwrecks. Surface finds in the wider Mafia Island area — including fragments of ceramics consistent with early Indian Ocean trade — suggest the region functioned as part of a broader network connecting East Africa with Arabia, Persia, and beyond. Gates came ashore here while investigating the possible location of Rhapta, a lost emporium described in ancient Greco-Roman texts as a major East African trading port, to meet a pair of researchers who had been working the waters around the island. Because no Wikipedia data is available for the bay itself, precise figures on the bay's dimensions or the number of documented wrecks cannot be confirmed, but the site sits at the center of an active, ongoing scholarly debate about where Rhapta actually stood.
The Periplus of the Erythraean Sea, a Greco-Roman merchant guide, describes a trading emporium called Rhapta somewhere along this stretch of the East African coast — a reference that forms the basis for modern searches in the Mafia Island region.
The wider Mafia Island region is believed to have been an active node in Indian Ocean trade networks, with maritime traffic linking East Africa to Arabia and South Asia, according to the broader archaeological record.
Gates films Season 13 Episode 5 of Expedition Unknown, "Chasing Africa's Atlantis," coming ashore at Chole Bay to meet underwater archaeologist Bridget Buxton and pottery expert Alexandra Ratzlaff.
The search for Rhapta is one of East African archaeology's more tantalizing open questions. The site is described in the Periplus of the Erythraean Sea — a first-century-AD Greco-Roman merchant handbook — as the southernmost major trading emporium on the East African coast, a place where ivory and tortoiseshell were exchanged and where iron tools were imported. Scholars have debated its location for generations, with candidates ranging from the Tanzanian mainland coast to the islands of the Mafia archipelago, but no site has produced the kind of material evidence — stratified Roman-era ceramics, monumental structures, or a confirmed harbor — that would settle the question.
On camera at Chole Bay, Professor Bridget Buxton makes the mainstream archaeological case clearly: if Rhapta was, as she puts it, 'the Amazon fulfillment center of the ancient world,' the physical evidence should be hard to miss. The Romans, she notes, 'weren't shy about leaving their footprint.' The absence of pottery in particular is damning for any proposed site, since ceramics are virtually indestructible and survive even catastrophic destruction. That reasoning led her and Professor Alexandra Ratzlaff to focus their search offshore rather than on land, using reported fishermen's sightings to target potential shipwreck sites — on the logic that ancient wrecks tend to cluster near the ports they were approaching when they foundered.
The underwater approach is methodologically sound and increasingly common in East African maritime archaeology, a field that has expanded significantly as diving technology has improved. The waters around Mafia Island remain relatively understudied compared to sites in the Red Sea or the Persian Gulf, which means genuine discoveries are still possible. Whether those wrecks, if found, could be definitively linked to Rhapta rather than to later medieval or early modern trade remains an open question — the material record would need to include datable Roman-era goods to make the connection stick.
Gates' episode contributed a useful on-camera summary of where the expert consensus currently stands: Mwamba Ukutu is probably not Rhapta, the search should focus on the seabed, and local knowledge is an underutilized tool. What the episode could not provide — and honestly presented as an ongoing investigation rather than a solved mystery — is a definitive answer about whether Rhapta lies anywhere near Chole Bay.
The Periplus of the Erythraean Sea, the ancient text that mentions Rhapta, was likely written by a Greek-speaking merchant mariner in the first century AD and is one of the earliest surviving navigational guides to the East African coast.
Mafia Island sits within a marine park that protects one of the larger coral reef systems in the western Indian Ocean, making the waters around Chole Bay as ecologically significant as they are historically interesting.
The strategy Buxton and Ratzlaff used at Chole Bay — interviewing local fishermen to locate underwater anomalies — is a recognized technique in maritime archaeology, since fishing communities often have generational knowledge of unusual seabed features.
The name 'Rhapta' is believed by some scholars to derive from a Greek word related to sewing or stitching, possibly a reference to the sewn-plank boat construction technique common to the region's ancient mariners.
Mafia Island is accessible by small aircraft from Dar es Salaam or by ferry, and Chole Bay itself is a recognized anchorage used by dhows and dive boats. The bay is generally accessible to visitors, and the wider Mafia Island Marine Park — which protects much of the surrounding reef system — is a draw for divers and snorkelers; check current entry requirements and marine park fees before visiting.
Dar es Salaam, Tanzania — approximately 120 kilometers to the north, accessible by scheduled light aircraft flights or boat.
The dry season from June through October is generally considered the most favorable time to visit, with calmer seas and better underwater visibility. The long rains from March through May can make boat travel rougher and reduce diving conditions.
Indian Ocean
The Indian Ocean trade network is the broader maritime system within which Rhapta — and the shipwrecks Gates and the team searched for at Chole Bay — would have operated.
Dwarka
Dwarka is another submerged or partially submerged ancient city investigated by Gates, making it a natural parallel for the underwater search for Rhapta.
Alexandria
Alexandria represents the Greco-Roman world that produced the ancient texts describing Rhapta, and Gates has investigated its legendary lost features, connecting it thematically to the search for a Roman-era East African emporium.