What is the visual effect of objects viewed underwater?

Objects viewed underwater generally appear larger due to the way light behaves when it passes from air into water. The refraction of light causes a bending effect, which can make objects seem closer and larger than they actually are. This is particularly important for divers to understand, as it affects how they perceive distances and sizes of marine life and underwater features. Being aware of this optical illusion helps divers make more accurate assessments about their surroundings, reducing the risk of misjudging sizes, which can be crucial for safety and navigation while diving.