You can take a train from Gare de Saint Jean in Bordeaux to Arcachon for around 7 euros, the train takes between 40 and 50 minutes.
Ungathatha isitimela kusuka eGare de Saint Jean eBordeaux ukuya e-Arcachon cishe i-7 euros, isitimela sithatha imizuzu eyi-40 ne-50.