Ho Chi Minh,
Just an hour and a half from downtown Saigon by hydrofoil, this is the closest beach town to the city. Don't go expecting anything approaching tropical paradise, however. The main beach here backed by concrete monstrosities (although some of the smaller strips of sand are reasonably pleasant) and the water is about as crystal clear as the plot of famously opaque TV series Lost
. Vung Tau is also known for its offshore oil and gas reserves and the presence of foreign workers has had the knock on effect of injecting a fair bit of sleaze into the equation. Having said all that, the town is actually a more than passable day trip from the big smoke.
There's fresh seafood aplenty in the backstreets away from the beaches while the views from the hills above town are tremendous. The area north of Vung Tau is even more alluring with some spectacular (and deserted) beaches awaiting exploration.