When it comes to watersports, nothing matches the serenity – or scenery – of gliding across a mountain lake on a stand-up paddleboard. On some Colorado lakes and reservoirs, stand-up paddleboarding is confined to a specific, relatively small area. However, there are several liquid oases where you can capture the full panorama of the surrounding peaks, forests and shores, and explore to your heart’s content. Here are some of our favorites. Grand Lake The largest and deepest natural water source in Colorado, Grand Lake measures 515 surface acres and is 265 feet at its deepest point.