Nan Madol: Ceremonial Centre of Eastern Micronesia

Significance

UNESCO describes Nan Madol as a series of more than 100 islets off the south-east coast of Pohnpei, built with basalt and coral boulder walls and containing stone palaces, temples, mortuaries and residential domains built between roughly 1200 and 1500 CE, the ceremonial centre of the Saudeleur dynasty. Its value is tied to megalithic architecture, evidence of chiefly societies and a continuing link to the Nahnmwarki system. It is inscribed under criteria (i), (iii), (iv) and (vi) and has been on the List of World Heritage in Danger since its inscription in 2016.

Current Status Rationale

Historical damage is documented in the site's record, but the current classification is based on present conditions and the most recent credible evidence. Nan Madol has been on the List of World Heritage in Danger continuously since its inscription in 2016, and the Committee retained it again in 2026 (48 COM 7A.25). The reasons recorded in the sources are overgrowth of vegetation and unchecked mangrove growth, siltation of canals, stonework collapse, storm surge exposure, and gaps in legal protection and management. Against that, the Committee in 2026 welcomed further vegetation removal, reopened canal routes and efforts to fund a Site Manager; adopted in 2025 a Desired State of Conservation for removal with eight corrective-measure areas and a five-year timeframe; and noted that resort construction in the buffer zone has ceased. The State Party's own January 2026 report, however, answers 10 of the 18 DSOCR items 'This has not yet been initiated' (the remainder report ongoing work, items under discussion or review, or partial progress) and says that major intrusive trees have not yet been removed or stabilised. Climate-related threats (sea-level rise, wave action) are named by the State Party and by the mission report but are not documented as having caused a specific recent damage event. Confidence is Supported rather than Confirmed: the Committee decisions are primary and consistent, but the Secretariat's and ICOMOS's 2026 assessment documents and UNESCO's 2025 and 2026 state-of-conservation web pages could not be retrieved, so the picture of current physical condition rests on the State Party's own report and on Committee decisions. Confidence does not alter the status.

Serious, currently active threats are documented, or major historical damage remains substantially unrepaired. Credible sources support this status, with some limits on corroboration.

Threat Categories

Historical Timeline

1. 2016
   Nan Madol inscribed on the World Heritage List and simultaneously on the List of World Heritage in Danger

   By Decision 40 COM 8B.22 (Istanbul) the Committee inscribed the property under criteria (i), (iii), (iv) and (vi) and placed it on the Danger List. The decision names overgrowth of vegetation, storm surge effects and some stonework collapse, and describes the condition of the stone structures as 'of extreme concern'. ICOMOS's evaluation had recommended inscription on the Danger List at the same time.

   Sources: UNESCO World Heritage Centre, ICOMOS (published on UNESCO World Heritage Centre)

2. 2017
   Committee retains Nan Madol on the Danger List (41 COM 7A.56)

   The Committee welcomed offers of expert support from France, Japan and the United States, noted that work on legislation LB 392 (which would establish the Nan Madol Historic Preservation Trust) had been delayed, and urged progress, urged appointment of a property manager, and noted the State Party's invitation of a joint World Heritage Centre/ICOMOS Reactive Monitoring mission.

   Sources: UNESCO World Heritage Centre

3. 2018-01
   Joint World Heritage Centre/ICOMOS Reactive Monitoring mission

   The mission, led by archaeologist Ian Lilley, reported that large trees and other vegetation damage structures, that canals are largely blocked (it said the main cause appears to be reduced seawater circulation after the causeway linking Temwen Island to Pohnpei was built, with mangroves trapping sediment), and that sea-level rise, storm surge and waves threaten the outer sea walls in places. It concluded that a full Desired State of Conservation for removal could not yet be defined. UNESCO's news item of 23 February 2018 describes the mission as having been held in January 2018.

   Sources: UNESCO World Heritage Centre / ICOMOS, UNESCO World Heritage Centre

4. 2018-09
   US Ambassador's Fund for Cultural Preservation grant of US$375,000

   UNESCO's news item of 9 November 2018 reports a September 2018 grant of US$375,000 from the US Ambassador's Fund for Cultural Preservation, and describes vegetation, silt in the canals and rising sea levels as risks to the site.

   Sources: UNESCO World Heritage Centre

5. 2023
   Committee retains Nan Madol on the Danger List (45 COM 7A.53)

   At its extended 45th session (Riyadh) the Committee said progress on a management and protection system had been slowed by COVID-19 restrictions, welcomed US Department of State Ambassadors Fund support for a two-year implementation programme, and was concerned that conservation problems had not yet been effectively resolved. It asked again for vegetation management and mangrove clearing in the main canals, a long-term Property Manager, legislation LB392, three plans, Heritage Impact Assessment (HIA) processes and a draft Desired State of Conservation for removal (DSOCR). It also expressed concern that a tourism resort on Nahnningi Island in the buffer zone had continued without a prior HIA.

   Sources: UNESCO World Heritage Centre

6. 2024
   Committee retains Nan Madol on the Danger List (46 COM 7A.39)

   The Committee credited vegetation removal, a completed Visitor Centre and draft plans, but said progress on essential issues had been limited despite earlier assurances. It said the property faces actual and potential danger from weak protection and management, overgrowth and stonework collapse, storm surges, erosion and siltation, and visitor impacts, and that resort work on Nahnningi Island had continued and expanded without an HIA. It asked for the DSOCR to be developed remotely for the 47th session. The State Party's report of 14 February 2024 had said Visitor Centre construction was complete but the centre was not yet open.

   Sources: UNESCO World Heritage Centre, Federated States of Micronesia National Commission for UNESCO (hosted by UNESCO World Heritage Centre)

7. 2025
   DSOCR, corrective measures and five-year timeframe adopted (47 COM 7A.19)

   The Committee adopted a Desired State of Conservation for removal from the Danger List comprising 18 conditions (for example vegetation cleared from access canals to five target islets, silted waterways cleared, retaining walls repaired, a climate change strategy, a permanent Site Manager, a revised Pohnpei State Code), together with eight areas of corrective measures to be completed within five years. It retained the property on the Danger List and called on the international community to support implementation.

   Sources: UNESCO World Heritage Centre

8. 2026-01-31
   State Party submits state of conservation report

   The report, signed by the FSM National Commission for UNESCO and dated 31 January 2026, describes ongoing vegetation clearance and canal maintenance, says canal routes have reopened between Nan Dowas, Pan Kadira and Para Nuii, and says that of the 18 DSOCR items, 10 are answered 'This has not yet been initiated' (including removal or stabilisation of major intrusive trees, a long-term silt plan, retaining wall repairs and opening the Visitor Centre). The report has no formal status column; the other items report daily vegetation and silt work, a completed and ongoing recognition of the Nahnmwarki, items under discussion or review, or partial progress. It names sea-level rise and stronger wave action as concerns and says the State Party is requesting technical support for a climate impact strategy. It does not describe any specific storm or damage event.

   Sources: Federated States of Micronesia National Commission for UNESCO (hosted by UNESCO World Heritage Centre)

9. 2026
   Committee retains Nan Madol on the Danger List (48 COM 7A.25)

   At its 48th session (Busan) the Committee welcomed progress on corrective measures, including further removal of intrusive vegetation, reopening of key canal routes and efforts to fund a dedicated Site/Property Manager. It noted that the Pohnpei State Government will not adopt the existing Site Management Plan and that a new one is to be prepared, and noted that construction of a tourism resort in the buffer zone has ceased, requesting an HIA before any decision on resuming work. It requested an updated state of conservation report by 1 February 2027 and decided to retain the property on the Danger List.

   Sources: UNESCO World Heritage Centre

Digital Preservation Index

Overall coverage: Moderate — Documented in several categories, with some notable gaps.

Three of five categories have publicly accessible evidence that was opened, which gives the moderate tier. Photography is UNESCO's public gallery only (12 images were visible on the page read, with more on further pages; 10 of the 12 credited to one photographer). Archival records are UNESCO's online nomination, ICOMOS evaluation, mission report and state-of-conservation documents. Scholarly coverage found is a 2015 full-coverage field survey of the islets, read via a bibliographic record. No publicly viewable 3D model or virtual tour was found: the undated airborne LiDAR presentation by the CSRM Foundation (hosted on doi.gov) shows that LiDAR imagery exists but does not state that the data are public, and the Google Arts & Culture page for Nan Madol was read as an overview with image assets and no tour, so neither was counted. Coverage is therefore thin on technical and immersive documentation.

• Photographic

  UNESCO World Heritage Centre public photo gallery for the property, showing islet walls, breakwaters, stone alignments, collapse of a perimeter wall and a blocked channel (12 images on the page read, with further pages; credits are mainly Osamu Kataoka).

  View source
• Archival Records

  UNESCO's ICOMOS evaluation of the 2016 nomination, available online with the nomination file and the January 2018 mission report on the property's UNESCO documents page.

  View source
• Academic Scholarly

  McCoy, Alderson and Thompson (2015), 'A New Archaeological Field Survey of the Site of Nan Madol, Pohnpei', Rapa Nui Journal 29(1), described as the first full-coverage field survey of the islets using high-precision GPS, with a GIS layer reported on tDAR (dataset not opened).

  View source

Law and commitments

• Treaty record for Micronesia