Hon Mun

Geography and the reef

Hon Mun lies about 10 km from Cầu Đá, about 45 minutes by boat according to the Vietnamese Wikipedia article^[1]. Wikidata gives coordinates of 12.1675, 109.305833, an elevation of 124 m and the GeoNames identifier 1574342^[2]. The Vietnamese article describes reefs at about 10 m depth and caves 10 to 15 m deep on the eastern side, where the rock is black like ebony (mun), the origin of the name, and where swiftlets nest^[1].

The Vietnamese article credits the protected area with about 350 coral species and about 1,500 species of marine fauna and flora^[1]. Nhan Dan gives more detailed counts for the protected area: over 350 species of reef-building hard corals, more than 230 reef fish species, 112 mollusc species, 112 crustacean species, 27 echinoderm species, 69 seaweed species and 7 seagrass species^[5][6].

The marine protected area

The Hon Mun Marine Protected Area Pilot Project was approved by the Global Environment Facility on 27 January 2000 with a grant of USD 972,447, executed by IUCN, and closed on 28 June 2006; its aim was to protect coral reef, mangrove and seagrass ecosystems and to develop methods for a national system of marine protected areas^[4]. The project's launch conference was held on 8 June 2001 and the management board of the Hòn Mun marine protected area was set up on 18 July 2001^[3].

On 12 March 2004 the area was renamed the Nha Trang Bay marine protected area, with an area of over 16,000 ha (160 km²) covering nine islands and the waters around them^[3]. The Vietnamese article on Hon Mun and Nhan Dan give the same total, about 160 km², split into about 38 km² of land and about 122 km² of water^[1][5]. Nhan Dan and its English edition describe it as Vietnam's first marine protected area, established in 2001^[5][6]. The bay itself was recognised as a national scenic site on 25 March 2005^[3].

Coral decline to 2022

In June 2022 Viet Nam News reported the survey figures presented to the Standing Board of the provincial Party Committee: in the north east and south west of Hon Mun live coral cover had fallen from 53.7% in 2015 to 32.62% in 2022, and in the south east and north west from 52.2% to 11.15%^[7]. Nhan Dan summarised the same decline as a fall from about 52% in 2015 to under 11% in 2022 in the south west and south east^[5], and its English edition reported that a June 2022 survey found declines of more than 70% at numerous locations compared with 2015^[6]. Báo Văn Hóa put the loss at 70 to 80% against the 2015 survey^[10]. The sources differ in how they label the zones.

The causes named by the provincial Party Committee were climate change, typhoon Damrey in 2017 and typhoon Rai (storm number 9) in 2021 on one side, and on the other lax management and poor coordination together with illegal fishing, illegal dredging, unregulated coastal construction and waste from tourism^[7][9]. Báo Văn Hóa also listed starfish outbreaks and thermal bleaching in 2019^[10].

The suspension of 27 June 2022

On 21 June 2022 the Standing Board of the Khánh Hòa provincial Party Committee concluded that press reports of the coral decline were accurate and directed that diving tourism in the vulnerable areas, especially around Hon Mun, be suspended so that the reef could recover^[7][8]; Nhan Dan identifies the document as Notification 347 of 21 June 2022^[5]. On 24 June 2022 the Nha Trang Bay Management Board announced that swimming and diving in the Hon Mun area would stop from 27 June 2022 until further notice^[9], and Tuoi Tre reported the decision of the Nha Trang City People's Committee covering all seven licensed dive points around the island^[8]. Nhan Dan lists the suspended activities as swimming, diving, boat trips and glass-bottom boats^[5].

On 7 November 2022 the provincial People's Committee issued a decision on a plan to restore the bay, including rapid surveys of the dive sites, removal of debris and repositioning of coral fragments, protection of turtle nests on Hon Tre and a plastic waste programme with UNDP^[10]. The city later directed the management board to install zoning buoys, signage and surveillance cameras to protect the reefs at Hon Mun and Hòn Chồng^[15].

Recovery and the rule since 2022

Surveys in late 2022 and March 2023 found live coral cover, hard and soft corals counted together, of about 74.5% in the north and south west of Hon Mun, within the 51 to 75% band rated good, with strong recovery of Acropora and soft corals in the north west and west^[14]. That figure is not comparable with the 2022 figures above: it counts soft corals as well as hard, the June 2022 report does not say what it counted, and the zones it pairs are not the pairs the 2022 survey used^[7][14]. In August 2023 the Nha Trang Bay Management Board proposed reopening a dive site on the south side of the island for registered professional operators and internationally certified divers only, under strict monitoring of numbers^[11][12]; days later its head said no formal proposal had yet been submitted and that reopening depended on scientific assessment, while a marine scientist cited a recovery time of at least 5 to 6 years^[13].

In February 2024 Tuoi Tre reported that diving at Hon Mun remained suspended, that a temporary dive site had been opened at Hòn Rơm instead, and that cover in the north west and north ranged from 30 to 50% with young corals growing on the broken reef^[15]. In February 2025 Nhan Dan reported quarterly monitoring dives by the management board and a coral nursery project approved for review in December 2024^[5].

In April 2026 Báo Khánh Hòa reported a provincial master plan to restore Nha Trang Bay to 2030 and the return of reef fish to the reefs, and of sea turtles, dolphins and whales to the bay since 2024^[16]. A survey by the management board's conservation department on 13 May 2026 found that the proportion of live coral, its density and its area had all increased, while the temporary dive point at Hòn Rơm continued with limited visitor numbers^[17]. A report of 20 May 2026 states that swimming and diving in the Hon Mun strict protection zone remained suspended, with many young colonies showing high survival; it gives no reopening date^[18]. No official decision lifting the suspension was found.