By Stephanie Longo | Wilkerson Pass, Colorado

By Jonathan Razo | Paredes, Portugal (30 km east of Porto)

By Jack Juliussen | Copenhagen, Denmark

By Dr Ski | Valencia, Philippines

By Maggie Romuld | Off the coast of Chile between Castro and Valparaiso

By Dr Ski | Valencia, Philippines

By Deirdre Horan | Dublin, Ireland

By Deirdre Horan | Dublin, Ireland

By Deirdre Horan | Dublin, Ireland

By Deirdre Horan | Dublin, Ireland

By Peter Lowenstein | Mutare, Zimbabwe

By Dr Ski | Valencia, Philippines

By Frank Lu | Veterans Park, Arlington, Texas, USA

By Frank Lu | Veterans Park, Arlington, Texas, USA

By Dr Ski | Sibulan, Philippines

By Dr Ski | Valencia, Philippines