"Secchi depth." YourDictionary, n.d. Web. 18 December 2018. <https://www.yourdictionary.com/secchi-depth>.
Secchi depth. (n.d.). Retrieved December 18th, 2018, from https://www.yourdictionary.com/secchi-depth
A measure of the clarity of water, especially seawater. Secchi depth is measured using a circular plate, known as a Secchi disk, which is lowered into the water until it is no longer visible. High Secchi depths indicate clear water; whereas low Secchi depths indicate cloudy or turbid water.