The lake is connected to the sea via three tunnels that lie near the surface. The tunnels channel tidal water in and out of the lake. Tide levels in the lake are damped to about a third of the lagoon tidal levels. The tidal peaks are delayed from the lagoon tidal peaks by about 1 hour and forty minutes. Biologist William Hamner estimated that about 2.5% of the lake's volume is exchanged during a tidal flow. However, because the tidal water enters at the surface, the lower anoxic layer is largely unaffected by tidal flows.