The Seawise Giant (later Happy Giant, Jahre Viking, Knock Nevis, and finally Mont) was an ultra-large crude tanker that set records as the longest, heaviest and highest-capacity ship ever built. At 458.45 m (1,504 ft) long, a 68.8 m beam, and 24.6 m fully laden draft, she displaced 657,019 tonnes at full load – a size so vast she could not transit the Suez or Panama canals.

With a deadweight tonnage of 564,763, she carried up to 4.1 million barrels of crude oil. Such scale – about 100 meters longer than Titanic and taller than the Empire State Building is high – made her an icon of maritime engineering.

Guinness World Records officially lists the tanker (as Mont, her final name) at 458.45 m length and 564,763 tonnes DWT, noting she was the largest ship ever constructed. In her long life (1979–2010) she earned a legendary status for her sheer size and for surviving extraordinary circumstances, as detailed below.

Timeline of Major Events

• 1974–79 – Construction: Ordered in 1974, built by Sumitomo Heavy Industries in Yokosuka, Japan and launched in 1979 as the 418,611 DWT ULCC Oppama. (Built on hull no. 1016, she encountered vibration issues in trials, causing her original Greek buyer to refuse delivery.)
• 1981 – Jumboization: Sold to Orient Overseas Container Line founder C. Y. Tung, who lengthened her hull (the “jumboisation” added over 80 m and 146,000 tonnes capacity) and relaunched her as Seawise Giant in 1981. Her capacity became 564,763 DWT with 46 oil tanks and 31,541 m² of deck area.
• 1988 – Iran–Iraq War Attack: While anchored off Larak Island (Iran) on May 14, 1988 carrying oil, she was struck by two Iraqi air-launched Exocet missiles during the “Tanker War” phase of the Iran–Iraq conflict. Fires ignited aboard and massive quantities of spilled oil burned out of control, destroying much of the ship’s superstructure. The crew abandoned ship; an Iraqi strike report noted she was “blazing out of control”. (At least one crewmember was killed and many reported missing.)
• 1991 – Salvage and Return to Service: Declared a constructive total loss after the war, the wreck was bought by Norwegian interests (Norman International A/S) and towed to Singapore for repair. By October 1991 she was fully restored, renamed Happy Giant, and returned to service. (A December 1990 photo shows her rust-stained hull in Hitachi Singapore drydock, bearing the scars of the 1988 attack.) Shortly thereafter owner Jørgen Jahre acquired her and renamed her Jahre Viking.
• 2004 – Floating Storage Unit: In 2004 the vessel was sold to First Olsen Tankers, renamed Knock Nevis, and converted into a permanently anchored floating storage unit (FSO) in Qatar’s Al Shaheen Oil Field. With her engines removed and accommodation gutted, she remained a stationary oil depot for years.
• 2009–2010 – Final Voyage and Scrapping: In late 2009 she was sold for scrap (renamed Mont and reflagged to Sierra Leone). On 21–22 December 2009 she sailed under her own power out of Qatar for India. After clearing customs she was beached at the Alang ship-breaking yard on 22 Dec 2009 to be dismantled. At 564,500 DWT and 458.45 m length she was officially “the largest ship ever to be scrapped”. The enormous break-up took roughly a year; scrapping was completed by late 2010. The ship’s 36-ton anchor was preserved and donated to the Hong Kong Maritime Museum.

Technical Specifications

Figure: Scale comparison of Knock Nevis (ex-Seawise Giant, red) against other large vessels (blue). The Seawise Giant was an ULCC (Ultra Large Crude Carrier) with truly unprecedented dimensions. Official registry data show her final length overall at 458.45 m, beam 68.8 m, depth 29.8 m, and full-load draft 24.611 m.

Her gross tonnage was 260,941 GT and 564,763 DWT, allowing about 4.1 million barrels of oil cargo. Propulsion came from two Mitsubishi V2M8 boilers and a Sumitomo-Stal Laval AP steam turbine (50,000 hp), driving a single enormous propeller.

Top speed was only around 16.5 knots – she was built for capacity, not speed. Her vast hull contained 46 separate oil cargo tanks, with roughly 31,541 m² of deck area. Fully laden, her 24.6 m draft prohibited passage through the Suez, Panama or even the English Channel.

Construction and Ownership History

The ship was laid down in 1974 and completed in 1979 by Sumitomo Heavy Industries in Yokosuka (Oppama Shipyard). She was originally ordered by a Greek shipping company, who named her Porthos in 1975 (keel laid as Porthos).

However, engine vibration problems and the owner’s bankruptcy left the partly-built hull unsold. The builders eventually sold her to Hong Kong tycoon C.Y. Tung’s OOCL (Orient Overseas) group, which took delivery in late 1979.

Initially named Oppama, she was soon lengthened (a 1980–81 “jumboisation” adding a 146,000-ton midsection) at Nihon Kokan shipyard, boosting her capacity to 564,763 DWT. In 1981 she was christened Seawise Giant (“Sea Wise” punning on “C.Y.’s” initials) and registered under the Liberian flag.

After surviving the Iran–Iraq War damage, the ship changed hands several times. In 1989 she was sold (as a wreck) to Norman International of Norway and renamed Happy Giant upon repair. In 1991 the Jahre family acquired her and she became Jahre Viking, flying the Norwegian flag.

In 2004 she was sold to First Olsen Tankers and refitted for Qatar’s oil fields, becoming the permanently moored Knock Nevis. Finally, in 2009 she passed to Amber Development (Singapore) and was renamed Mont for one last voyage to Alang, India.

Role and Fate During the Iran–Iraq War

The Seawise Giant played an inadvertent role in the 1980–1988 Iran–Iraq War. In the spring of 1988, during the so-called “Tanker War,” both Iran and Iraq targeted neutral oil tankers to disrupt each other’s oil exports. On 14 May 1988, the giant tanker was anchored at Larak Island (an Iranian offshore terminal) loading Iranian crude when Iraqi warplanes struck.

According to contemporary reports, two Iraqi jets attacked the 564,739-ton Liberian-flag Seawise Giant, hitting her with air-launched missiles. The ship erupted in fire; seawater and spilled oil around her also burned fiercely. By late afternoon she “was still blazing out of control,” leaving observers to describe her as “on fire everywhere”.

The burnt-out hull of Seawise Giant at Hitachi Shipbuilding’s Singapore yard on 27 December 1990, undergoing post-war repairs.

The fiery attack forced most of the crew to abandon ship; reports vary, but at least one sailor was killed and many were initially unaccounted for. Contrary to some later rumors, Seawise Giant did not permanently sink in deep water: after the raid she drifted and burned, but remained afloat in shallow water. With firefighting crews extinguishing the blazes, the remaining oil cargo was transferred off the hull. Nevertheless, she was declared a constructive total loss – essentially a wreck too damaged to sail economically.

Politically, the attack was part of Iraq’s campaign to blockade Iran’s oil exports. The U.S. later noted that Iraq had declared “exclusion zones” in the Gulf and considered any tanker “servicing the port of a belligerent” (like Iran) as a legitimate target. Thus Seawise Giant, although neutral-flagged, was caught in the crossfire.

Her survival, however, became remarkable: after the war ended (August 1988), she was still salvageable. In 1989 a Norwegian consortium (led by Norman International) bought the damaged vessel, towed her hull to Singapore, and arranged a complete rebuild. By October 1991 she was back in operation as Happy Giant, proving that even the largest ship could be brought back from apparent doom.

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Later Commercial Service and Decommissioning

Once restored, the tanker resumed decades of commercial service under new names. As Happy Giant (1991–1994) and then Jahre Viking (1994–2004), she carried oil for various Norwegian shipping interests. During the 1990s the ship operated worldwide, though always limited by her draft.

In 2004 she was sold to Singapore-based First Olsen Tankers and renamed Knock Nevis. In this configuration she ceased ocean voyages: converted into a floating storage/offloading unit, she spent 2004–2009 moored at Qatar’s Al Shaheen oil field, serving as a stationary offshore tanker. In that role she held oil until it was needed, effectively storing millions of barrels for the field operator. (By 2008–09 Knock Nevis was said to be “worth $100–125 million” as a floating terminal.)

By the late 2000s the economics of operating such a behemoth had changed. In December 2009, after 30 years of history, she was sold for scrap. Reflagged to Sierra Leone and renamed Mont, she was towed to India for dismantling. On 22 December 2009 she was beached on Alang’s breakers’ beach in Gujarat – incidentally, the same yard that had previously demolished her smaller sister Jahre Viking.

With her vast red hull settling on the sand, she officially became the largest ship ever to be scrapped. Officials noted her deadweight (≈564,500 tonnes) and overall length (458.45 m) and declared, “Mont is yet to get mandatory clearances… After it arrives at Alang … this would be the biggest vessel to be scrapped in Alang”. Dismantling was carried out in phases from late 2009 through 2010. By year’s end 2010 the last plates of steel had been cut.

The only physical remnant saved from the giant was her massive anchor. The 36-ton anchor – originally installed when she was the 657,019 DWT Jahre Viking – was removed before scrapping and shipped to Hong Kong. In 2010 it was placed in the Hong Kong Maritime Museum’s collection, and by 2025 it was moved to a public anchor plaza on Victoria Harbour, commemorating her link to Hong Kong’s maritime heritage.

Legacy and Cultural Impact

The Seawise Giant/Knock Nevis set records that have yet to be equaled in normal shipping. She is remembered in Guinness World Records as the longest ship ever constructed and the highest-capacity tanker. In 2015 Guinness noted her dimensions (458.45 m, 68.8 m beam) and that her 564,763 DWT capacity was unmatched.

Technically, only much later purpose-built floating structures exceed her length – e.g. the 488 m Shell Prelude FLNG – but among self-propelled vessels she remains peerless. For decades she was routinely cited in publications as “the largest ship ever built”. Press accounts highlighted that her length exceeded iconic structures – for example one report noted she was longer than the Empire State Building is tall.

Her story captured public imagination. The Seawise Giant was featured in engineering blogs and trivia articles as an example of extreme scale – one writer quipped that her only rivals in size are some small islands. Her dramatic wartime attack and miraculous recovery have made her a subject of maritime lore. The ship has appeared on postage stamps and in documentaries.

Technically minded enthusiasts note her heavy engines and rudder (230-ton rudder, 50-ton propeller) as marvels. When compared to other ships, her scale is stark: for instance a modern large container ship (Maersk Mc-Kinney Møller, 399 m) is dwarfed in the comparison image above. In quantitative terms, no oil tanker since 2009 has come close; planned ULCCs over 500,000 DWT were ultimately not built.

Culturally, Seawise Giant symbolizes the petroleum age’s extremes – a single ship that could carry roughly 5% of the world’s daily oil needs. Her 36-ton anchor’s display in Hong Kong, a city tied to the ship’s early ownership, serves as a maritime monument.

She has made cameo references in Guinness and engineering charts, and modelers and shipping history buffs continue to admire her. As one analysis noted, the Seawise Giant’s only peers in “longest vessel” comparisons are floating structures, but she remains the largest moving object ever built. In sum, her legacy is the embodiment of “supership” – a testament to human engineering, still holding the title of the largest ship ever built.