Do: Buy a watermelon. August is the month to do it, when sweet melons from the south of Russia — Dagestan, Volgograd, Astrakhan and Rostov — are shipped into the city and put into their 200 or so street cages. The price in the city is fixed at 20 rubles per kilogram. Watermelon connoisseurs say that a melon is ripe and sweet when the stalk is dried out and when you tap it and hear a hollow sound. If you don't trust your watermelon-sounding abilities, you can ask the vendor to cut a small piece to taste.
Don't: Go to the newly opened Mosquarium — yet. The lines and crowds are nightmarish. But definitely go with the whole family when the novelty wears off, and when you have some disposable cash. Weekend tickets can be up to 3,200 rubles (about $50) for a family of four, so you might consider weekday or the even cheaper weekday morning visits. But it's a beautiful place, with 80 tanks and 8,000 sea creatures, from tiny shrimp and starfish to terrifying sharks. You can wander along underwater tunnels or get up close, wet and personal in one of the many interactive areas. Or you can get really wet by sitting in one of the first rows of the theater for the special show featuring orcas, belugas, dolphins, seals and many other trained sea creatures. In August the shows are only held once a day on Friday, Saturday, and Sunday, although they will be adding a Thursday show too. Tickets for the water show are separate and range from 900 to 2,100 rubles ($14-33). For more information and ticket purchases, see moskvarium.ru, or call the information line at 499-677-7777 (recorded messages in English).