Trespass Unisex Strapper Small Beige Travel Holiday Office Bag with Shoulder Strap

can u tell me size of bag please

Would this be suitable for the gym? Perhaps a small face towel, 500 ml bottle? I live close to a gym, so don't need large towel, change of clothing,et

Is the bag waterproof in very heavy rain?

I have 2 dogs, is it big enough to hold balls,spare leads, purse & mobile.