This Divers Underwater Notebook Wrist Slate is great for snorkeling or scuba diving. It helps you tell your dive buddy what you're seeing by simply writing on the face of this easy-to-use underwater communication device. It features a contoured slate with Velcro arm straps which fits conveniently onto your wrist. It also features a 3-layer slate made of ABS plastic so you have more than enough space to write. This writing slate is a simple yet effective way of communicating underwater.