So we did this this week, and it was about a 3 minute walk from shell beach to the children's pool

Easiest is to ask your smart phone "when is low (or high) tide" once you are in San Diego. Otherwise look it up on the web: Shell Beach San Diego on Tideschart (sorry, TA doesn't allow URLs): Should bring you to their site: United-States California San-Diego-County Shell-Beach

Lots of small shells left as high tide recedes. The Pacific Ocean drops some nice ones, but I wouldn't plan a shelling trip there. You are better off doing a tide pool excursion.. Lots of critters to see.

Formally, there is to be no removal of anything from coastal parks or properties, so no shells, rocks, sea animals (starfish, anemones, etc.). With that being said, I think there are probably small caches of memory-shells in nearly all bedrooms across the country of children who have visited San Diego or Coronado beaches. Sometimes it's also very special to take pictures of all the great shells and make collages or photo cards to share with loved ones.... that's also a very nice way of both maintaining memories and sharing them, while honoring the park policies to the letter. Enjoy the beaches!

There is a steep flight of concrete steps from street level to the beach. If you get there at a very low tide indeed, there will be a large expanse of shallow water (not exactly your classic tide pools) with lots of interesting creatures, but not immediately spectacular. Some of the rocks will be slippery with algae, as is almost always the case in a low-tide-with-rocks situation. If you are worried about safety, you could go to the Scripps Aquarium instead -- it's a fabulous aquarium and they have some outdoor fake tide pools that are very nice, but you can't pick up the critters. Don't bother with Shell Beach unless the tide is VERY low (like a minus tide) otherwise the "tide pool" areas will be knee deep or waist deep in water.