On island Korcula you can arrive with a ferry from Orebic or Split or Lastovo.

from Orebic ferry nummber 634 to Dominca (Korcula).
634 Orebić - Dominca.
The journey takes about 15 minutes.
TIME TABLE: 634 Orebić - Domince - click here

Prices:
approximately 15 per car + driver (high season) - one-way ticket
approx 4 euros per adult - one-way ticket

You can also reach Korcula with ferry from Split. The ferry drives approximately 4.5 hours

From Split by ferry 604 to Vela Luka (Korcula), and then further Ubli (Lastovo).
604 Split - Vela Luka (Korcula) - Ubli (Lastovo).
Drive to the town of Vela Luka takes about 4 hours.
TIME TABLE: 604 Split - Vela Luka (Korcula) - Ubli (Lastovo) - click here

Prices:
approx 70 EUR for car + driver (high season) - one-way ticket
about 10 EUR per adult - one-way ticket

From Split by catamaran 9604 to Vela Luka (Korcula), and then further to Ubli (Lastovo).
9604 Split - Vela Luka (Korcula) - Ubli (Lastovo).
Ferry drives to the town of Vela Luka takes cca 2.10 hours.
TIME TABLE: 9604 Split - Vela Luka (Korcula) - Ubli (Lastovo) - click here

Prices:
about 10 EUR per adult - one-way ticket

From Split by catamaran (9608) to the town Korcula (Korcula) goes through the town Hvar.
9608 Split - Hvar - Korcula.
Ferry drives to the town of Korcula about 2.30 hours.

Prices:
approximately 22 EUR per adult - one-way ticket