SM UC-70


Heritage Category: Maritime Wreck

List Entry Number: 1446103

Date first listed: 18-Aug-2017

Location Description: 5.2km north-west of Whitby, off Overdale Wyke, North Yorkshire


Ordnance survey chart of SM UC-70
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Location Description: 5.2km north-west of Whitby, off Overdale Wyke, North Yorkshire


Latitude: 54.52663000

Longitude: -0.66891000

National Grid Reference: NZ8624515409


The wreck comprises the remains of UC-70 – a coastal minelaying submarine commissioned into the German Imperial Navy in November 1916. The submarine conducted 10 patrols and sank/damaged 40 ships during the war before being bombed and depth-charged on 28 August 1918 with the loss of all hands.

Reasons for Designation

The UC-70 is designated a Protected Wreck Site for the following principal reasons:

Historical: the UC-70 is representative of the Type UC II class of submarines; the most successful submarine design in history, and has a clearly understood history of service and loss;

Archaeological: major component parts of the submarine remain in-situ, both internally and externally, including the presence of skeletal human remains;

Vulnerability: component parts of the submarine, artefacts and its crew remain vulnerable to uncontrolled salvage.


UC-70 conducted 10 patrols laying small minefields and sinking/damaging 54,591 tons of Allied shipping during the war. Commanded by the 29 year-old Oberleutnant sur Zee (Sub-Lieutenant) Karl Dobberstein, holder of the Iron Cross (First and Second Class) and the Friedrich-August Cross, the submarine left Zeebrugge on 21 August 1918 to undertake mine-laying operations on the convoy route between Holland and England and, subsequently, to head to the East coast of England to attack Allied shipping there.

Seven days later, a Blackburn Kangaroo bomber of 246 Squadron sighted a long trail of oil while on anti-submarine patrol off Whitby. The origin of the oil slick was traced to an elongated shape beneath the surface, which the pilot identified as a probable submerged U-boat. The destroyer HMS Ouse arrived at the scene shortly after witnessing the aircraft’s bombs exploding and proceeded to drop depth charges in the vicinity of the large patch of oil that had accumulated on the surface. Between seven to ten depth charges were dropped by the Ouse and more oil and pieces of debris were observed on the surface.

From reports of the initial investigation by Royal Navy divers searching for intelligence material, and the fact that all the hatches were found open at the time of the discovery, it is reasonable to believe that at least part of the crew tried to escape. The bodies of three of the crew, including the commanders, were recovered by divers in September-October 1918. The divers found no mines in the chutes, so although the activities of UC-70 in the days prior to its sinking are not reliably known, it seems likely that its mine laying operations had been successful or that they were jettisoned.


Designation History: Designation Order: No 773, 2017 Made: 18th July 2017 Laid before Parliament:19th July 2017 Coming into force:18th August 2017 Protected area: 30 metres within 54 31.5987 N 00 40.1346 W

No part of the restricted area lies above the high-water mark of ordinary spring tides.

History: With the restriction imposed on offensive U-boat operations in the summer of 1915, and its virtual cessation in the autumn, the significance of the mine-laying U-boat became more prominent. The UC II class followed and was conceived in the summer of 1915 when the U-boat Inspectorate developed Project 41, consisting of a new and larger 400-ton minelayer to replace the 160-ton UC I type. Although slight variations existed between individual vessels built by different yards, each of the type UC II minelayer class U-boats conformed to the same overall specifications: they were double-hulled with improved range and sea-keeping compared to the UC I type. They were armed and carried 7 torpedoes and up to 18 mines with other modifications; such as two propellers. Two engines increased their reliability by reducing the risks connected with engine failure resulting in more effective patrols. The design of the UC II class therefore represented a larger and improved version of the Type UC I and combined with an upgraded power plant meant that the whole British coast was now within range. If judged only by the numbers of enemy vessels destroyed, the UC II is the most successful submarine design in history. Estimates indicate that they sank more than 1800 enemy vessels.

Description: Remote sensing and diving investigations in 2016 revealed that the UC-70 lies in an upright position with a slight list to port. The outer pressure hull of UC-70 is corroded away in many places and numerous plates are detached, although the inner hull appears to be largely intact. The ribs of the port and starboard fuel and ballast tanks are also largely intact, although many of the plates have become corroded or detached. The 88mm deck-gun is still intact and in place and the openings of the six mine-laying tubes are visible on the upper surface of the hull. The bow section of the outer hull, forward of the mine-laying tubes is badly damaged – most likely as a result of HMS Ouse’s depth charges – although the bow hydroplanes and a number of steel plates now lie on the seabed. The two bow torpedo tubes were not found on deck. The conning tower plating has fallen to the port of the submarine but the two periscopes are still visible and in situ within their sleeves.

Human remains were observed at an exposed section at the stern and comprised the top of an adult cranium and part of the shaft of a humerus or femur – possible belonging to the same individual and, given their location at the stern of the submarine, may be those of a torpedo man, stoker or machinist (narrowing down identity to six or seven crewmen). Unusually, a Chinese plate dated to the reign of the Emperor Kangxi (1654 - 1722) was recovered from the submarine's galley in 1993. It is possible that this plate relates to a crew member who served or had contacts at the German naval base at Tsingtao, captured in 1914 and an important Far East base for the Germans.


Books and journals
Eberhard Rössler, 1 (Author), Harold Erenberg, 2 (Translator), The U-boat: Evolution and Technical History of German Submarines, (1981)
Dive Whitby - The UC-70, accessed 27/03/2017 from
Original Documents from the National Archives, Kew: ADM 186/407 - German Navy, Submarines, April 1918, accessed 10 April 2017 from
PastScape record, accessed 27/03/2017 from
Wrecksite.EU, accessed 11/04/2017 from
Wessex Archaeology (2017) UC-70, off Whitby, North Yorkshire, field assessment report for Historic England

End of official listing