ほかにもあるだろうけど ここにいろいろある

https://www.telegraph.co.uk/travel/destinations/europe/france/cote-d-azur/saint-tropez/articles/st-tropez-gettingthere/


Another option is to drive to St Raphaël or Ste Maxime, leave your car there and take the ferry across the bay. In St Raphaël catch the Bateaux de St Raphaël shuttle service (see above). In Ste Maxime, make for the Bateaux Verts (00 33 494 492939; bateauxverts.com) at 14 Quai Léon Condroyer. It’s around 15 minutes to St Tropez: €7.50 one way, €13.50 return (children four - 12 years old, €4 one way, €7.50 return). Bâteaux Verts also run summer services from Port Grimaud, Marine de Cogolin and Les Issambres. Check the website.