18. Lake Tahoe – California/Nevada, USA

Lake Tahoe is a showstopper year-round, but come summer, its clear, cool waters steal the spotlight. Head to Sand Harbor for the best mix of wide sandy beaches and jaw-dropping blue hues. Paddleboarding here feels like gliding over glass. Whether you’re in waist-deep or deeper, the water remains crystal clear. With rugged granite rocks and alpine forests framing the lake, it’s one of America’s top spots for those craving both adventure and tranquility.