Begin your trip in Thiruvananthapuram by visiting the famous Padmanabhaswamy Temple, an architectural marvel built in the Dravidian style of architecture. This temple is dedicated to Lord Vishnu and is famous for its 100 feet long gopuram, intricate carvings, and beautiful murals. You can also witness the daily rituals and puja done by the temple priests.
Spend a leisurely day on Kovalam Beach, one of the most popular beaches in India. You can indulge in water sports, sunbathing, and beach walks. Also, visit the Kovalam Lighthouse which is located on a hillock overlooking the Arabian Sea. The lighthouse offers a panoramic view of the sea and surrounding areas.
On your last day in Thiruvananthapuram, explore the city's colonial past by visiting the Napier Museum. The museum has an eclectic collection of artifacts, ancient sculptures, and bronze idols. After the museum, you can head to the Thiruvananthapuram Zoo which is home to several rare and exotic species of animals like Bengal tigers, Indian rhinoceros, and Nilgiri langurs.
If you have more time, you can also consider visiting the Shanghumukham Beach, Vizhinjam Rock Cut Cave, and the Kanakakunnu Palace. However, if you have less time, you can skip the Kovalam Lighthouse and Thiruvananthapuram Zoo. Make sure to carry sunscreen, hats, and sunglasses as Thiruvananthapuram can get quite hot during the day.