Large incoming tides can also even create surfables waves in river systems and bays, called tidal bores ! The Amazon, Severn in the UK, and Qiatang in China are just a few rivers around the world with rideable tidal bores.pring tides occur when the influence on the ocean from the Moon and Sun are in sync, causing extra-high high tides and low low tides-neap tides, when the difference between high and low tide is more mellow, occur when the Moon and Sun bulges are out of sync.