Sestao River

The original Sestao Sport Club, in existence since 1916, went under in the summer of 1996 with debts it could not pay.

The Verdinegros wear green and black vertical stripes over black shorts, the same colours the badge carried before the collapse.

Sestao River itself reached Segunda División B for the first time in 2004. In 2013/14 the club won its group outright, then lost the promotion play-off and missed the second tier. Progress resumed later: the group win in Segunda Federación in 2022/23 sent the club up to Primera Federación, and in 2024 Sestao River took the Basque phase of the Copa Federación de España, beating SD Gernika Club in the final.

Home games are played at Campo Municipal de Las Llanas, which holds 4,367. The club has no official place in Athletic Club's pyramid — that role sits with Bilbao Athletic — but the two have worked together for years under Athletic's Cantera con Valores scheme.