BOSTON (AP) — This year's running of the Boston Triathlon marks an important milestone for the race, now in its eighth year.

About 1,500 competitors are expected to participate in one of three races Sunday, including for the first time in the history of the event an Olympic distance race.

The day also includes a sprint race and a kids' race for children ages 7 to 15.

The USAT-sanctioned event starts and ends at Carson Beach in South Boston.

The Olympic distance event includes a 1.5-kilometer swim in Dorchester Bay, a 35-kilometer looping bike ride along Day Boulevard and a 10-kilometer run.

The sprint race is a 750-meter swim, a 17.5-kolimeter bike ride and a 5.5-kilometer run.

The triathlon is sponsored by Columbia Threadneedle Investments.

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Online: Boston Triathlon, http://www.bostontri.com