The annual military endurance competition was launched on Tuesday, this time in the northern town of Rakvere.
Over four days beginning today, participants will have to cover a course whose straight-line distance is 120 kilometers, staving off a variety of mock opponents and simulated threats.
As in every year, there are many teams from NATO countries and other neighbors, a fact that Brig. Gen. Meelis Kiili, the commander of the volunteer Defense League - the main organizer - mentioned in remarks at the opening ceremony.
Twenty-six teams are taking part, nine of which are from foreign countries: three from Denmark, two from Finland, two from the US, one from Sweden and one from Lithuania.
Several segments are open to spectators: near Rutja airfield on Friday and the final sprint on Saturday through Rakvere.
The head umpire is a Finnish reserve officer, 1st Lieutenant Tomi Haimelin.
The Admiral Pitka Recon Challenge is held in a different location and course each year to neutralize what has been Estonian participants' considerable home-field advantage.