Grand Bois tide times

Grand Bois is a coastal village on Réunion's south coast, in the commune of Saint-Pierre, where the island's volcanic landscape meets the Indian Ocean without the reef barrier that protects the west coast from Saint-Gilles to Saint-Leu. The south coast of Réunion is geologically younger and more exposed than the west: lava flows from Piton de la Fournaise have reached the sea here on several occasions in recent decades, creating new coastal formations and extending the land into the ocean. The black volcanic rock and occasional red oxidised flow surfaces are the characteristic coastal geology of this southern section.

Saint-Pierre, the main town of Réunion's south coast 5 km west of Grand Bois, is the island's second urban centre: a seafront promenade on a black-sand and shingle beach, a marina (Port de Saint-Pierre) with berthing for pleasure craft and the occasional inter-island connection, and a Saturday morning market that is one of the most visited in Réunion. The market sells tropical produce — lychees, vanilla, pineapple, chouchou (chayote), palm heart — alongside local prepared foods. The seafront at Saint-Pierre is pleasant in the evening; the black sand beach is the accessible swimming option for the south coast.

Grand Bois beach is a black volcanic sand beach used primarily by locals from the southern communes. The exposure is to the south and southeast, into the direct Indian Ocean fetch without reef interruption, and the wave regime here is more energetic than the west coast lagoon. The beach is not lifeguarded; swimming is best in calm conditions when swell is below 1 m. The lava rock headlands on each side of the beach offer good rock platform access at low water — urchins, crabs, and small reef fish in the lava pools.

The south coast is beyond the main tourist infrastructure of Réunion, which concentrates on the west coast. This makes it a local coast: fewer visitors, less organised beach infrastructure, and a more direct experience of the volcanic landscape that is Réunion's geological reality. The road south from Saint-Pierre through Saint-Joseph and around the Piton de la Fournaise lava zone to the eastern Côte Sauvage (wild coast) is one of the more dramatic coastal drives in the southern Indian Ocean region.

The Indian Ocean tidal regime at Grand Bois is mixed semidiurnal: mean spring range 0.8 to 1.2 m. The south coast sees the full Indian Ocean swell exposure; even on calm days a 1 to 1.5 m southerly swell runs along this coast. Rock platform access at low water requires calm sea conditions — the combination of a low tide and 2+ m swell makes the rock platforms genuinely dangerous. Tidal planning for rock activities here requires both the tide prediction and the swell forecast from Météo-France La Réunion.

Predictions on this page come from Open-Meteo Marine, a gridded global ocean model. Accuracy is typically within plus or minus 45 minutes on timing and 0.2 to 0.3 m on height — at Grand Bois's 0.8 to 1.2 m spring range, the height uncertainty is 20 to 30 percent of the total signal. SHOM publishes the authoritative harmonic tide tables for Réunion; the nearest reference station is Saint-Pierre.