I am also confused with your lighting in temples. I never heard about such lighting arrangements inside the temples over the water. It is new to me.
Do you know this? In Kanyakumari, Goddess Bhagavathi had a pearl nose stud which was so powerful that the mariners used to think it as a light house. Many mariners were confused and were stuck between the rocks. Due to this the gate was locked forever, to save the mariners.
No life without Sun