There are no roads or cars on Ilha do Mel, so getting in means a boat.
From Pontal do Sul on the mainland, a regular ferry crosses to either Nova Brasília or Encantadas. The crossing takes about 30 minutes. Pontal do Sul is reached by bus from Paranaguá (an hour) or, less frequently, direct from Curitiba. Buses are timed to ferries but check the day's schedule.
From Paranaguá, a longer and less frequent ferry sails through the bay. The crossing is more scenic — passing fishing villages and the protected mangrove channels — but takes nearly two hours.
Once on the island, you walk. Sandy tracks connect the settlements and the beaches. Bring only what you can carry; wheelbarrows are available at the piers if you're carrying heavy luggage to a pousada.