Formerly listed as Gwiyagal (D63) in AUSTLANG.
Besold (2012-13:70) reports that Gweagal is the name of one of the social groups residing on the northern arm of Botany Bay (around La Perouse) and whose language is a northern dialect (D63) of Dharrawal S59. She also says that Gweagal is possibly a variant spelling of guya-gal 'south-belong', that is 'southerners' of the Kurnell Peninsula.
Capell (1970:21) says Gwiyagal (D63) is probably a dialectal form of Thurrawal S59, having a distinct vocabulary. Eades (1976:3) comments that it seems most unlikely there was any distinct dialect or language called Gwiyagal, suspecting that it was probably the name of a local group.
See also Southern Dharawal S58.
As noted by Wafer and Lissarrague (2008:109, 165-166), Gwiyagal was often confused with Geawegal E1. Consequently, some of the resources identified as Geawegal E1 may actually be Gwiyagal.
South shore of Botany Bay, possibly limited by St. George's River (Capell, as cited in Oates 1975:199) ... northern arm of Botany Bay (around La Perouse) (Ray Ingrey p.c., in Besold 2012-13:70)
Speaker numbers were measured differently across the censuses and various other sources listed in AUSTLANG. You are encouraged to refer to the sources.
Speaker numbers for ‘NILS 2004’ and ‘2005 estimate’ come from 'Table F.3: Numbers of speakers of Australian Indigenous languages (various surveys)' in 'Appendix F NILS endangerment and absolute number results' in McConvell, Marmion and McNicol 2005, pages 198-230 (PDF, 2.5MB).