How old are you children? Define "close". One hour? Two? Four? Do you have any idea of what do you want to do with your children when you get there?

Ages would be great. As would time of year you will be here.

Hi,

4 children from 5 to 11 and it would be the first week of April, i would like a lake or something similar and 2 hrs max driving time

Then head to Highway 74 and drive through the Cleveland National Forest to the Lake Elsinore area. See link above.

http://www.castaiclake.com/aboutus.html

Here's a map: Less than an hour's drive from L.A. -- simple route, north on Interstate 5 to exit 176A.

http://mapq.st/14Ph7G9

No lake, but at the beginning of April, I would choose Joshua Tree National Park. It is pretty fantastic - joshua trees are weirdly shaped yucca trees and only found in that part of the world, really. Lots of amazing rock formations that look so out of place and moon-scape-ish! Easy hiking, plenty of wildflowers, near Palm Springs.

http://www.nps.gov/jotr/index.htm

If you want a lake, I'd head to Big Bear, up in the mountains (you would head east on the the 210 or 10, then there are a couple routes you could use to go north). It's probably at about your 2hr limit. Not a park, but a lake and cute little town, and much nicer, I think, than Lake Elsinore (although that drive to Lake E is nice).

Just FYI, the LA metropolitan area is almost as much of a sprawl as Mexico City. Although there are some nice and sizeable urban parks, you have to drive pretty far to get to a real national park or similar.

The nicest lake would be Big Bear, as Janazz said. It's in a small mountain community about 120 miles east of LA. But it will be chilly up there in April as it is over 6,000 ft elevation. Take a jacket.

Big Bear lake at the beginning of April will be, IMO, very boring! It is great for winter activities and okay for summer, but I can't imagine what a family with 4 kids could do there in April. But you can enlighten me and the OP if you could suggest specific activities.