The Black Diamond Football League (BDAFL) is situated on the east coast of Australia in the state of New South Wales. It is north of Sydney and covers an area of more than 150 lineal kilometres from Terrigal Avoca in the South to Nelson Bay in the north. The Muswellbrook Club is 70 minutes drive west of Newcastle.
It was formed at the end of the 1999 season with a combination of clubs from the Central Coast and Newcastle Football Leagues.
The league comprises 15 clubs. Five of the clubs are Upper Hunter based, five in the Newcastle area whilst another five are on the Central Coast. The most northern club in the league is Nelson Bay, Muswellbrook is the most Western and the most southern is Gosford.
In 2018, the competition consisted of a senior men's competition (Black Diamond Cup) with 11 teams; senior men's reserve grade competition (Black Diamond Plate) with 14 teams; a women's competition (formed in 2015) with 16 teams and a social competition with 4 teams.
The premiership trophy in the league is the Black Diamond Cup which was first played for in 1888 and won by the Wallsend Club. The trophy is said to be the oldest Australian sporting trophy still being contested even outdates cricket's Sheffield Shield and is housed in the Newcastle Museum.
The League has an Umpires Association and both the Central Coast and Newcastle have junior competitions.
The BDAFL is administered by an independent Board of Management who oversee all aspects of the competition. The day to day activities are managed by a part time Football Operations Manager.
The league is regarded to be one of the strongest leagues, both on and off the field in NSW/ACT.