Sure, here's an ideal itinerary for one day in Kollam:

Morning:

• Start your day with a visit to the Thangassery Lighthouse. This lighthouse is located on a rocky promontory and offers stunning views of the Arabian Sea. You can climb up to the top of the lighthouse for panoramic views of the surrounding area.
• After visiting the lighthouse, head to the nearby Thangassery Beach. This is a beautiful beach with golden sand and clear blue waters. You can take a stroll along the beach or simply relax and soak up the sun.

Afternoon:

• For lunch, head to the local market and try some of the delicious seafood that Kollam is famous for. There are plenty of restaurants and street food vendors selling fresh fish, prawns, crabs, and other seafood delicacies.
• After lunch, visit the Ashtamudi Lake. This is a large freshwater lake that is surrounded by lush green forests and coconut groves. You can take a boat ride on the lake and enjoy the scenic beauty of the surroundings.
• Next, visit the Kollam Beach. This is another beautiful beach with soft sand and calm waters. You can take a dip in the sea or simply relax on the beach and watch the sunset.

Evening:

• In the evening, head to the Mahatma Gandhi Park. This is a beautiful park with well-manicured lawns, colorful flower beds, and a musical fountain. You can take a leisurely walk in the park or simply sit and enjoy the serene atmosphere.
• Finally, end your day with a visit to the Kollam Temple. This ancient temple is dedicated to Lord Shiva and is known for its intricate carvings and architecture. You can attend the evening prayer ceremony and witness the traditional rituals performed by the priests.

That's it! With this itinerary, you'll be able to explore the best of Kollam in just one day.