The U-28 "Sea Crocodile": Forstner's Monster at the Sinking of SS Iberian, 1915

Summer 1915. The German submarine U-28 was at sea in the Western Approaches, commanded since August 1914 by Kapitänleutnant Georg-Günther Freiherr von Forstner. Its target was SS Iberian, a Leyland Line cargo steamer carrying general cargo from Manchester to Boston with a crew of 67.

30 July 1915. Nine miles south by west of Fastnet, off County Cork. The torpedo struck the stern. In Forstner's words, "The steamer sank so swiftly that its bow stuck up almost vertically into the air." The wreck stayed under for about 25 seconds. Then came an explosion, and debris flew up out of the sea.

So did something else. A gigantic sea animal was flung 20 to 30 meters into the air. Six officers of the watch stood in the conning tower, among them the chief engineer, the navigator and the helmsman. Forstner said they all pointed it out to each other at once. Senior engineer Romeihs watched through binoculars. The distance was about 150 to 100 meters, in bright sunshine.

"The animal was about 20 meters long and crocodile-like in shape," Forstner wrote, with pairs of strong front and hind legs adapted for swimming and a long head that tapered towards the nose. It had a long pointed tail. After 10 to 15 seconds it sank out of sight. No photograph was taken. "We were unable to identify the creature, but all of us agreed that it resembled an aquatic crocodile."

Forstner stayed silent for more than 18 years. Then, on 19 December 1933, in the middle of the Loch Ness craze, the Deutsche Allgemeine Zeitung printed his account. An illustrated version followed in 1934, and in 1935 he added material to a German edition of Rupert Gould's Loch Ness book. Robert Maas, the cook, was said to be the only other witness to survive the war. Maas never wrote a word.

In 2010 historian Mike Dash examined the U-28 war diary. It notes two torpedo hits, gunfire, smoke, four dead and 61 survivors. It records no explosion and no animal. Forstner's own Journal, published in 1916, does not mention the Iberian. The survivors spoke to British, Irish and American newspapers. None mentioned a creature.

Palaeontologist Darren Naish calls the story a fabrication. Later versions placed the explosion at about 500 fathoms, which he argues makes the scene physically impossible. An orca of about 10 meters leaps about 5. He also suspects the 1934 drawing was modelled on a stuffed baby crocodile.

Bernard Heuvelmans took the opposite view. He ranked the case among the four most reliable sea serpent sightings and suggested a surviving thalattosuchian, a marine crocodilian, startled at the surface by the explosion. Willy Ley suspected Loch Ness publicity explained the timing. Others have proposed a mosasaur, a pliosaur or misread debris. Defenders note that Forstner reportedly stuck to the story for life.

U-28 did not survive the war. On 2 September 1917, while shelling SS Olive Branch, it was destroyed when the steamer's munitions cargo exploded. All 39 crew died. Popular claims that a monster sank it are false. The wreck of the Iberian lies about 104 m down, protected under Irish law.