The most extraordinary rainbow

Have you ever seen anything like this?

I was in Pontianak, West Kalimantan on the island of Borneo. It lies directly on the equator (I saw the monument and straddled the line!). After about 2 hours on a boat ride down a very dark watered river, we arrived at our destination - a palm oil plantation that sits on a peat dome (hence the dark water). After walking around and discussing the environmental impacts we looked up to see this amazing site! A completely circular rainbow! I'm not sure if this is something that only happens at the equator or not, but it's spectacular and I am really glad to have seen it!