Catch an evening/overnight train from Bengaluru (Yesvantpur or KSR City) to Mangaluru so you wake up on the coast; book 2A or sleeper as suits your budget. Overnight travel saves daytime and is comfortable in December.
Either eat on the train (some trains have pantry service) or bring a packed dinner; choose light, easy-to-eat items for a comfortable overnight journey.
Arrive at Mangaluru station and take a local passenger train or KSRTC bus north to Udupi (about 1–1.5 hours). Travelling early gives you a full day on the coast.
Enjoy classic Udupi breakfast (dosas, idlis, neer dosa and strong filter coffee) at a well-known local restaurant — a good introduction to coastal Karnataka cuisine.
Visit the historic Sri Krishna Temple, famous for its unique worship style and prasadam; temple visiting hours are normally 6:00am–12:30pm and 5:30pm–8:30pm, so morning is ideal.
Drive/auto to Malpe Jetty (10–20 minutes), then board the ferry to St. Mary's Island — ferries typically run roughly 9:00am–4:00pm (last returns vary), so take the early afternoon boat; the island is famous for hexagonal basalt rock formations and clear water.
Have fresh coastal seafood (try pomfret or mackerel) at a reputable beach shack or restaurant in Malpe; seafood is at its best when freshly caught in this region.
Visit Kaup (Kapu) Lighthouse and beach — the lighthouse grounds are generally accessible 8:00am–5:30pm and offer panoramic views of the coastline and a photogenic wooden pier.
Explore Kodi Bengre for serene backwater views where the swath of the Souparnika / Seetha rivers meets the sea; great for photography and short boat rides (confirm local boat availability).
Drive ~45–60 minutes north to Maravanthe, a scenic beach with the highway between sea and river — ideal for a late-afternoon stroll and photos during golden hour.
Have an early breakfast and complete checkout; keep luggage ready for the train — many hotels offer early check-out in December season but confirm during booking.
Arrival back in Bengaluru in the evening; collect luggage and head home or to your next destination. December trains fill quickly—plan seat preferences in advance.