There were 70 - 80 executions in Thingvellir from the 17th century onwards. Of those there are recorded 15 hangings, 30 beheadings and 18 women were drowned in the so called 'Drowning Pool' which was where the bridge across the river is now. It is the only place of execution which is marked by a memorial plaque but there are also places at Thingvellir with self-explanatory names such as Gallows Rock (Gálgaklettur), Scaffold beach (Gálgaeyri) and Burning gap (Brennugjá).
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George Plantaganet, brother of Edward IV and Richard III. Tradition has him murdered in 1478 by drowning in "butt of Malmsey wine" in the Boyer Tower. The legend is carried through by Shakespeare in Richard III.

St John of Nepomuk. Martyred by drowning in the Vlatva 1393 on site of Charles Bridge

The Paris "Massacre of 1961" - during the Algerian War somewhere between 40 and 200 pro FLN Algerian demonstrators were driven into the Seine and drowned (some may already have been killed). In 2011 a plaque was unveiled on Pont St Michel stating " De ce pont, et d'autres ponts de la région parisienne, des manifestants algériens furent jetés dans la Seine le 17 octobre 1961, victimes d'une répression aveugle...."