Career
He represented his nation Iceland in two editions of the Olympic Games (2000 and 2004), and has also been training throughout most of his sporting career for Þytur Sailing Regatta (Icelandic: Siglingaklúbburinn Þytur). Geirsson made his official debut at the 2000 Summer Olympics in Sydney, where he placed forty-second in the Laser class with a Netto grade of 355, after having decided to pull himself out in the last race due to yachting malfunction. At the 2004 Summer Olympics in Athens, Geirsson qualified for his second Icelandic team, as a 24-year-old, in the Laser class by granting a tripartite invitation from the International Sailing Federation.
Sailing through the race series with a similar effort from the previous Olympics, Geirsson recorded a satisfying grade of 344 Netto points to upgrade his position to fortieth in a fleet of forty-two sailors.
Hafsteinn Geirsson is also a cyclist.