"The wet shoe is the one that was in the water."
Translation:La scarpa bagnata è quella che era nell'acqua.
I would say they are almost the same. Your sentence is grammatically correct but, as already stated by cmccluskey, you forgot the definite article. Also, there is a slight difference in meaning between "scarpa umida" and "scarpa bagnata". It it's like if "scarpa bagnata" had a little larger quantity of water than "scarpa umida"