Dye was released 5 times near the s

Dye was released 5 times near the sea surface at the seaward edge of the surf zone, with incident wave heights between 0.5 and 0.9 m. Small amounts of the dye were entrained in, and transported shoreward by, every breaking wave or bore, resulting in a faint streak of dye stretching onshore from the area of highest dye concentration to the shoreline. However, the seaward edge of the dye could be advected seaward (out of the surf zone) or shoreward by water movements not directly associated with the passage of individual bores. In every case, the drifter moved offshore or onshore with the seaward edge of the dye, and remained in or near the area of highest dye concentration (as observed visually). Similar results were observed with water-filled balloons. In three releases, the smaller balloons (0.2-m diameter) always advected shoreward with bores, while the larger balloon (0.5-m diameter) was not entrained in bores and moved offshore or onshore, usually in conjunction with the drifter. Differential cross-shore velocities, estimated from the drifter–large balloon cross-shore separation after a few minutes, ranged from 10 to less than 1 cm s21. These dye and balloon tests suggest that the drifter cross-shore velocities are similar to those of near-surface water particles that are not entrained in bores.