Can anyone give me some info re:internet cafes or such (is there wifi in public places)? I'll be on a ship which stops in various locations and hope to access internet at rates lower than the shipboard prices

I know how to find/recognize these type of places in Thailand, etc. but not so savvy about my chances of finding places with limited time in port in Vietnam - I'll be in Saigon, Hanoi and Da Nang