Seven tourists were canyoning when a wave about 3m high hit them - the guide was among those killed, while two in the group were rescued.
President's two-day visit is being closely watched on mainland, amid fears that giving island too much autonomy could fuel a breakaway bid.
Political strength of nationalists means question of island’s status may have to be finally addressed by Paris.
Protest organisers said up to 25,000 people attended the demonstration in the island's capital Ajaccio ahead of Tuesday's presidential visit.
Elections to decide the makeup of a new regional assembly on the French Mediterranean island of Corsica have resulted in a resounding win for an alliance of nationalists who want greater powers of autonomy and the introduction of preferential treatment for locals, such as in access to housing.
Group led by autonomist leader Gilles Simeoni won 45.36% of the votes for newly-created, more powerful local assembly on French island.
Forest fires which have already destroyed 2,000 hectares on the French Mediterranean island since Friday were still burning on Sunday.
Authorities in the Côte d’Azur region moved people out of tents, campsites and holiday homes around the hilltop town of Bormes-les-Mimosas.
It has requested two additional Canadair water bombers to add to the 19 aircraft currently battling the flames.
Hundreds of homes were evacuated as a precaution as the island of Corsica, the town of Carros near Nice and Saint-Tropez were badly hit.
Fans from Corsican side Bastia twice invaded the pitch during the League 1 match against Lyon, when a steward was suspected of joining a group who attacked the visiting players, forcing the match to be delayed and finally abandoned.
Incident led to removal of more than a dozen people and the evacuation of a hall in Ajaccio after a demonstration against her presence on island.
Five men were handed jail terms, suspended for four of them, over the racially-charged August incident which pitched three brothers of Moroccan origin against members of a local village angered by their attempt to block off a beach.
Move to uphold ban 'on security grounds' is first such ruling since France's highest administrative court overturned another ban on the swimsuit.