Cloisters is a wonderful park full of trails leading to the ocean. We love Cloisters because it is right off the bike trail so we can ride our bikes to the park. The wooden play structure is small but great for younger children. The structure is over sand (rather than wood chips) which makes for some fun times with sand toys. The trails that surround the park are great for the little ones who have bikes to ride. There is also a huge grassy area and picnic tables for parties. The park is clean and well kept with a natural feel about it. The biggest downfall is that it is often very windy and cold so bring a jacket!
The Cloister's park is located between hwy 1 and the ocean. It has a large spacious grassy area with a bike path around it. It's all in easy view, so your kiddos can ride and you can feel safe with them doing so. The playground is semi handicapped accessible and is clean and newer. My son loves the playground and picnic tables (don't leave your food unattended or the sea gulls will get it). The bathrooms are clean and the parking area is close by if you forget something. It's also a great park for flying kites or setting off small kid rockets. :)
Cloisters park has a very nice play structure and bathrooms, and it is *almost* on the beach. There are great walking paths connecting this park with multiple beach accesses and natural and manmade water drainage ponds and creeks. There is a very large grassy area for playing with frisbees etc. The structure itself is nice and is surrounded by recycled rubber pavement. There are also infant swings.
There are also a few picnic tables and barbeques.
The downside of this park is that there is no shade and fog can come in quickly from the ocean. I've seen birthday parties disappear in the fog. Be sure to bring lots of sunscreen, hats, and warm jackets for quick changes in the weather. All in all, I prefer to play at Del Mar park. But if you want to combine the day with the beach, this is the one to pick.