Some outdoor attractions are accessible not far from Riga, During summer it is luge track. It is longest in all the Baltic states and also with seven curves. You can catch scenic view while you go uphill because later when you go downhill you need to think only about speed :). There is also good tavern where you can enjoy meal and atmosphere after luge. In winter here is ski track, but I never tried it.
1 way up and down costs 0.70 Ls