It is advisable that you eat and drink only where you cannot be seen by Muslims.

Straight approach: if you are familiar with the neighborhood, you can simply ask them if they feel offended by eating by the pool or not. The same applies to the gym.

At my work, most of the Spanish staff asked me if I feel offended by them eating & smoking in front of me, and I told them I don't mind at all.

Smoking also is prohibited for Muslims in Ramadan.