Thistlebrig, on the River Tay near Perth, Scotland, is really two waves depending on the flow. At low to medium water it's Wee Eric on river right — a clean, glassy, forgiving green face with an easy eddy to work from, great if you're still finding your feet. Push the flow higher and Wee Eric washes out, handing things over to the main Thistlebrig wave on river left: a massive, fast, bumpy, high-volume ride that wants a big board under you. Either way, come with a high-volume surfboard or SUP, since this spot doesn't reward anything small.