We have a 4 year old and twin 1.5 year olds and this sandbox is big enough for everone with room to play. We only put 150 pounds of sand in it and it was perfect. If we had put all 300 pounds in, it would have filled it up to the top. No wind storms yet, so we have not tested out the lid yet (but it keeps out the rain perfectly). We get up to 80 mile an hour storms at our place, so my husband is looking into some lid latching options. Something should work. It is well made.