Tekun Guinea shine yankin arewa maso gabas na yankin Tekun Atlantika mai zafi daga Cape Lopez a Gabon, arewa da yamma zuwa Cape Palmas a Laberiya. Yankin mahada na Equator da Prime Meridian (latitude da longitude digiri) yana cikin gulf. Daga cikin koguna da yawa da ke malala zuwa Tekun Guinea sun hada da Nijar da Volta. Yankin bakin teku da ke gabar teku ya hada da Gwanin Benin da na Bonny. Asalin sunan Guinea ana zaton yanki ne a yankin, ko da yake takaddama game da takamaiman sunan Bovill (1995) ya ba da cikakken kwatancen: Sunan Guinea galibi ana cewa ya kasance lalatacciyar hanyar sunan Ghana, waɗanda theasar Portugal suka karɓa a cikin Maghreb. Marubucin na yanzu bai yarda da wannan ba. Sunan Guinea ya kasance ana amfani dashi duka a Maghrib da Turai tun kafin lokacin Yarima Henry. Misali, a taswirar kwanan wata ta 1320 ta mai zane-zanen Genoese Giovanni di Carignano, wanda ya samo labarinsa game da Afirka daga wani ɗan ƙasa a cikin Sijilmasa tsohon garin ciniki a Arewacin Afirka, mun sami Gunuia, kuma a cikin atlan Catalan na 1375 a matsayin Ginyia.