Acerronia Polla

[1] Tacitus' account indicates that Agrippina the Younger had set sail on a cruise on which Nero had secreted conspirators intent on killing her.

Agrippina and Acerronia, along with the steersman Crepereius Gallus, were underneath a canopy on deck which had been secretly weighted with lead.

At a given signal, the canopy fell, killing the steersman, but missing Agrippina and Acerronia because of the high-backed couch they had been sitting on.

[2] There had been a mechanism designed to scuttle the ship, although it malfunctioned, and the conspirators failed in their further efforts to sink the craft.

[2] The account of Cassius Dio is fundamentally the same, although he does indicate that the boat was in fact scuttled, and that Acerronia drowned.