Ma'anar ƙamus na kalmar "kasashen teku" tana nufin ƙasan tekun, wanda za a iya raba shi zuwa yankuna ko yankuna daban-daban, irin su continental shelf, continental slope, abyssal plain, da ramukan teku. Gabaɗaya ƙasan tekun yana rufe da siminti, duwatsu, da sauran nau'ikan yanayin ƙasa, kuma gida ne ga nau'ikan rayuwar ruwa daban-daban, gami da halittu masu zurfin teku kamar ƙaton squid, tsutsotsin tube, da nau'ikan kifaye iri-iri. Nazarin benen teku wani reshe ne na nazarin teku da aka sani da bathymetry, kuma ya ƙunshi amfani da kayan aiki da fasaha daban-daban don taswira da gano bakin teku.