The eastern harbour — Ptolemaic royal quarter, Antirrhodos and Cape Lochias under the modern port.

The Ptolemaic royal quarter — what we know.

The Ptolemaic royal quarter occupied the southern and eastern arc of the eastern harbour and the Antirrhodos island within it. The classical sources (Strabo, Pliny, Diodorus Siculus) describe a complex of royal palaces, formal gardens, the Soma mausoleum that supposedly held the body of Alexander the Great, the Caesareum temple, and the famous Library of Alexandria's main collection-rooms. Most of this quarter is now under the modern Alexandria eastern harbour at depths of six to ten metres. The institutional expeditions — initially Honor Frost's pioneering 1960s work and then Jean-Yves Empereur's Centre d'Études Alexandrines from the late 1980s onward — have catalogued approximately two thousand identifiable structural features in this area, with significant disagreement among scholars about which features correspond to which named buildings in the classical sources.

Antirrhodos island.

Antirrhodos was the small island in the eastern harbour that hosted, according to Strabo, a Ptolemaic royal palace and possibly the famous Cleopatra-era palace from which the last Ptolemaic queen reigned. The submerged remnants of Antirrhodos sit roughly in the centre of the modern eastern harbour at depths of six to seven metres. The island's footprint is clearly defined on the seabed by a granite-block kerb that follows the original waterline, with the residual building foundations spread across the enclosed area. The journal's reports here concentrate on the kerb's structural integrity (which is the institutional team's running concern) and on the foundation-stub field within the kerb.

Cape Lochias.

Cape Lochias formed the northern arm of the eastern harbour — the rocky peninsula that with Pharos island defined the harbour's entry. Today the cape's modern continuation is the Silsila promontory with the headquarters of the Alexandria coastal authority on its surface. The submerged section of Cape Lochias extends roughly four hundred metres seaward of the modern shoreline, with palace foundations, formal-garden retaining walls, and a notable artificial cave (the "Lochias grotto") that may have served as a Ptolemaic royal banqueting space or as a religious sanctuary.

What our field reports cover here.

The eastern harbour survey is the journal's broadest file in geographical scope, the longest in the running total of reports, and the most active in terms of year-round dive scheduling because the harbour conditions allow productive work in more weeks of the year than the open-coast sites at Heracleion or Canopus. The one hundred and eight reports distribute across the three main areas of the survey: the southern royal-quarter foundation field (forty-six reports), the Antirrhodos island remnants (thirty-three reports), and the Cape Lochias submerged section (twenty-nine reports).

The modern-harbour overlay problem.

The eastern harbour's submerged archaeological context is, more than any other site we document, overlaid by the modern working port — anchor strikes from moored vessels, dredging operations to maintain navigation depth, and the periodic harbour-construction projects that the Alexandria coastal authority undertakes. The institutional teams have documented at least eleven recent damage incidents (mostly from anchor strikes) to known archaeological features in the past decade. The journal flags damage incidents in our reports and forwards the documentation to the Centre d'Études Alexandrines, which is the institutional contact point for the coastal authority's heritage liaison. This is one practical area where our real-time field reporting genuinely adds value to the institutional record — the institutional teams cannot dive year-round, and our shorter dive seasons sometimes catch damage incidents earlier than their next institutional season would.

The sea-level rise context.

Sea-level rise at the Alexandria coast — approximately 18 cm since 1980 and projected to add 30 to 60 cm by 2080 — affects the eastern harbour submerged record in two ways. First, the documented features are now slightly deeper than they were in the institutional teams' early publications, which complicates direct citation of depths across decades of work; we always note the year of measurement in our depth readings. Second, the modern-harbour operational depth is being maintained against the rising sea level through more frequent dredging, which puts the submerged archaeology under increasing pressure from the dredging operations. The 2025 season summary covers this in more detail.

The companion file on the Pharos lighthouse blocks covers the specific eastern-harbour block field at the harbour mouth. The Heracleion-Thonis file and the Canopus file cover the related Canopic-mouth sites west of Alexandria. The journal's methodology applies across all four sites.