Who are the two Gaza flotilla activists abducted by Israel?

Two activists, Saif Abu Keshek and Thiago Avila, members of a Gaza-bound humanitarian flotilla, have been presented before an Israeli court after being abducted by Israel in international waters near Greece. They were intercepted along with 175 other campaigners, but only they remain in detention. Abu Keshek, a Spanish national of Palestinian origin, has been organizing Palestinian solidarity movements across Europe for over 20 years.