A comprehensive survey on aquatic and semiaquatic bugs (Heteroptera: Nepomorpha and Gerromorpha) of three Greek holiday islands, Rhodes, Crete and Corfu, was conducted from 2007 to 2010 at 237 localities. In this paper, hundreds of detailed records for 30 taxa in nine families are given. The occurrences of Rhagovelia infernalis africana Lundblad, 1936 and Velia mariae Tamanini, 1971 are confirmed and recorded for the first time from Europe sensu stricto. Additionally, some notes on morphology, taxonomy and distribution of the European species of Rhagovelia and Velia are also given, Velia mariae is recorded for the first time not only from several Greek islands, but from continental Greece and Bulgaria as well. Gerris asper (Fieber, 1860), a common European species, was also found for the first time in Greece. Furthermore, new occurrence data are given for endemic taxa; Sigara nigrolineata mendax Heiss & Jansson, 1986 and Velia rhadamantha rhadamantha Hoberlandt, 1941 (whose distribution is restricted to Crete and small adjacent islands) are very common throughout Crete, whereas Ilyocoris cimicoides jonicus (Lindberg, 1922) apparently is rare in Corfu.
Keywords: Hemiptera, distribution, faunistics, endemic species, Mediterranean basin, Balkan Peninsula, Velia rhadamantha rhadamantha, Velia mariae, Rhagovelia nigricans nigricans, Gerris asper.