San Diego's coldest months deliver its clearest water, its warm summers turn hazy and green, and the cleanest water almost always lives offshore and at depth. Here's how to read the seasonal inversion and the permanent inner-versus-outer gradient so you pick the right day, spot, and depth.

Can you actually predict dive visibility? You can predict the odds — honestly and usefully — if you stay local and keep score. Why global “exact number” apps overpromise, and how we built ours to be honest about uncertainty instead.

Laguna's coves face southwest, which makes them especially exposed to south swell. Here is why long-period south swell wrecks shallow-cove visibility, which sheltered spots still hold up, and how to read a forecast into a go or no-go.