Take a bus to Laem Chabang port (100 THB, 1 hour from Pattaya), then ferry to Koh Si Chang (50 THB, 45 minutes). This cargo port route offers a different perspective compared to the tourist-oriented Sri Racha pier departure, and you'll encounter more working boats and local commuters during the journey.

The island has royal palace ruins, decent beaches, and locals who aren't trying to sell you stuff constantly. Rent a motorbike taxi for island tours (200 THB for 2 hours) or just walk around the main village. Ferry runs every hour 6 AM to 7 PM.

Laem Chabang route tends to be less crowded than Sri Racha departures and gives you a proper industrial port experience before reaching the peaceful island. Way less touristy than Koh Larn either way you get there.