Who are the two Gaza flotilla activists abducted by Israel?

Two activists, Saif Abu Keshek and Thiago Avila, from a Gaza-bound humanitarian flotilla, have been detained by Israel after being abducted in international waters near Greece. They are currently on a hunger strike in Shikma Prison in Ashkelon. The court in Ashkelon has approved a two-day extension to their detention, prompting calls for their release from the Global Sumud Flotilla and condemnation from various governments and rights groups. The activists were intercepted by Israeli forces in international waters off Greece.