Take a boat ride on the Singapore River. The boarding point is at Water B, near Fort Canning Park. We bought tickets for 4 people (parents and two children) through Klook, which was almost 400 baht cheaper than buying on-site. I don't recommend buying in advance; it's better to check the weather first to see if it's suitable for a boat trip. Luckily, on the day of our 6:30 PM cruise, the sky was clear, no rain, no sun, and a pleasant cool breeze. The view was stunning.