This type of breaking wave forms over gentle slopes, characterized by long slow breaks and white water spilling over the crest. What is it called?

The type of breaking wave described in the question is indeed a spilling breaker, which forms over gentle slopes and is characterized by its long, slow breaks and the white water that spills over the crest. This phenomenon occurs when waves encounter a gradual shallowing of the seabed, which allows them to rise and break smoothly. The energy of the wave dissipates more gradually in this process, resulting in a less violent break where the crest of the wave gently spills over the rest of the wave rather than plummeting straight down. Spilling breakers are often seen in areas with a gentle gradient, making them suitable for beginner surfers and more manageable conditions for various water sports.