Are there grocery stores between Cancun and Tulum? We want to put up bottled water, beer, wine, general snacks. We'll be staying in Tulum area, so closer to Tulum will be great. Thanks.

I believe there's a Chedraui (super-market) and a Sam's Club in Playa del Carmen.

for the chedruai - these directions are from locogringo: When coming south from the airport, as you approach Playa del Carmen you will go through two sets of traffic lights. As you go through the second set, you will see a big shopping plaza on your left, it is orange. Keep going south and you will come to a "Returno" which will allow you to U turn and go north. Take the U Turn and stay in the far right lane, and you can enter the plaza from there.
or there is an even newer, bigger store now. pass the chedruai and then sams club, both on your left. shortly after sams, on your right is another mall with grocery. i can not recall it's name. there are 2 sets of lanes traveling south at that point. if you get into the right hand lanes at the 3rd light you can make a right turn into the parking lot.
if you drink milk be sure and stock up as you will probably not find any in tulum. this store has a good liqour section plus deli & bakery. fyi -interesting bakery set up. you grab what looks like a pizza tray and some tongs and select your items, then take all to a counter where someone will bag and price for you. they will deal with pesos or dollars - the cash register does the math.
there is a smaller grocery in tulum - a san fransisco i think. no one speaks any english and the selection is not like chedruai or home but it's there at least. there is another even smaller store just outside the archway into akumal - they have milk. i don't recall much for wine in akumal or tulum but they have beer.
be sure and have lunch or dinner at mezzanie. they have a salad with pine nuts and bleu cheese that was delicious. great setting. dandy mojito.
almost at the end of the tulum beach road on your right is a sand road out to the beach. you can actually drive on this part of the beach which is kinda cool. have a great trip.

There is a new mall on the right(west) side of 307 on your way south to Tulum which has a large grocery store called Soriana which should serve your needs. It is just past the Playacar entrance and you will need to be in the local lane of traffic to exit into the mall. If you miss the turn there is a turn around on the left side of the highway just down the road.

soriana is the store i could not recall the name of.

In Tulum, there's the San Francisco supermarket right along hwy 307.