The season's over, I'm afraid, but for the autumn, join the Qatar Natural History Group (membership details in 'Marhaba' magazine) 'cos they do field trips and rambles when it's not too hot. There's also a sailing club and a diving club. details again in marhaba. To explore on your own, just head to any coast, except around Doha. Try the Singing Dunes (Marhaba again) and the West coast.