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Magdalena Bay · Mexico · Wreck

USS H-1 (Seawolf) Wreck

Sunk twice in twelve days: aground in 1920, refloated, gone in 45 minutes

A 46-metre (150-foot) United States Navy submarine of the First World War era, lost off Magdalena Bay in March 1920: she ran aground on a shoal, was refloated twelve days later and sank again within 45 minutes in about 15 m of water. Dive The World lists her among the wrecks at Isla Santa Margarita, alongside the Second World War merchant ship SS Westbank Park. The wreck was identified again in 2019.

Also known as USS Seawolf, H-1 Submarine Wreck.

Where it is and how deep

Depth profile of USS H-1 (Seawolf) Wreck: typical dive to 15 m (to 50 ft) 18 m · Open Water30 m · Advanced40 m · Recreational limit15 mtypical dive
Depths on a shared scale to 40 m (130 ft); dashed lines mark common certification limits.

24.4150° N, 111.7890° WApproximate position — the dashed circle shows where the site lies; your operator's briefing has the mooring.

The dive

No dive plan for this wreck has been published, and no source describes a route across the hull. What is documented is its shape and setting: a submarine 150 feet (46 m) long, sunk in roughly 15 m of water off Isla Santa Margarita. That depth puts the whole wreck inside a single no-decompression dive with gas to spare, so the work here is finding the hull and reading its condition rather than managing a profile.

Treat the depth figure with care. The 15 m is from the 1920 loss report, the water the submarine went down in 45 minutes after being refloated, and no later survey confirms it matches today's seabed. The position is not published either: the wreck was identified south of Baja California in September 2019, but the coordinates shown here are an island anchor rather than a surveyed mark. Anyone planning to dive it needs a local boat, a position, and a look at the hull's present condition first.

The wreck

Vessel
USS H-1 (Seawolf)
Type
World War I H-class submarine
Length
46 m (151 ft)
Built
1913
Sunk
1920
Cause
Ran aground on a shoal off Magdalena Bay on 12 March 1920; refloated on 24 March but sank again 45 minutes later
Lies
Sank in about 15 m of water off Isla Santa Margarita; present-day attitude unrecorded

USS H-1, also commissioned as USS Seawolf and known as Submarine No. 28, was the lead ship of her class in the United States Navy. On 12 March 1920, working up the coast of Baja California, she ran aground on a shoal off Magdalena Bay; four men, including her commanding officer, died trying to reach shore. The repair ship USS Vestal refloated her on the morning of 24 March, but she sank again within 45 minutes, in some 50 ft (15 m) of water. Her wreck was identified south of Baja California in September 2019.

Marine life and season

The sources we used don't single out particular species here.

Month-by-month season rating for USS H-1 (Seawolf) Wreck
JanFebMarAprMayJunJulAugSepOctNovDec
Off-seasonOff-seasonOff-seasonOff-seasonOff-seasonOff-seasonFairFairGoodPrimePrimeGood

Season follows Magdalena Bay: The baitball season runs Oct–Dec and peaks in November; outside it the marlin disperse and operators do not run trips.

Know before you go

  • No published position for the wreck and no operator running to it: it has to be located and assessed on site before anyone dives it.
  • The recorded 15 m is the depth the submarine sank in in 1920, not a surveyed present-day depth, so plan gas and profile for a deeper possibility.
  • Dive The World rates currents here as gentle inside the bay but potentially strong in the open ocean, with swell on the seaward side of the islands.

Questions divers ask

How deep is the USS H-1 wreck?+

The 1920 loss report puts the submarine in some 50 ft (15 m) of water. No later survey confirms that this is the depth at the wreck today, so treat 15 m as the recorded figure rather than a measured one.

Can you dive the USS H-1 submarine?+

Dive The World lists her among the wrecks at Isla Santa Margarita, but no source describes an operator running trips to the submarine itself, or the state of the hull today. Diving in Magdalena Bay is sold as a liveaboard cruise out of San Jose del Cabo.

Sources

  1. USS H-1 — Wikipedia
  2. Magdalena Bay Diving, Baja California — Dive The World
  3. 2019 in archaeology — Wikipedia
  4. Isla Santa Margarita — OpenStreetMap

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