Nha Trang is famously Vietnam’s best beach resort city, and it’s also among the cheapest places in Southeast Asia for the essentials. Diving is quite good and prices are very reasonable, and even the small “beach clubs” on the sand will rent you a comfortable lounge chair for the day and serve you drinks for very little.
There are no real hostels in Nha Trang, and that’s mostly because hotels are so cheap and plentiful in the bottom end of the range. Hotels in the small tourist district are lining the streets at very low prices, and hotels in the older tourist area just to the north are even more reasonable. High-end chain hotels are as expensive as they are most everywhere else, so the city is more of a bargain for those on a tighter budget.
Food is more geared to Western audiences than it is in other Vietnamese cities, and it’s rarely great but it’s often good and portions are usually generous. Beer is cheap everywhere, and mixed drinks in bars and clubs are very reasonable compared to similar places in any other part of the world.