How do you manage taking three (or more) toddlers out when they all run in different directions once they are out of the pushchair?

On the days when this is likely to happen, we just go to a field for our daily outing. It's enclosed and has nothing to climb on etc. so whilst I am trying to train them all up, it doesn't matter too much if they go in different directions, or if one wants to run ahead while another wants to stop and look at the daisies. My days are increasing though with this particular trio and I don't want to have to go to the enclosed field every day. Any tips?