I don't think there are elephants in Vietnam. This question was asked recently and that was the answer.

Do a Google search for elephant and Vietnam, and you will find quite a few sites about their occurence in that country. Many of the sites are concerned with preservation, which does not fit with tourist rides.

A few years ago we spent some time travelling in Vietnam and visited Lak Lake near Buon Ma Thuot in the central highlands - we stayed at "Royal Palace of Boi Dai" less impressive than it sounds.

The main reason for visiting that area was to explore a few of the minority peoples villages in the area and around Pleiku. Whilst at the lake itself there were elephants around the lake which seemed mostly to be working elephants and were obviously well treated. We did get to ride one right accross the lake at sunset which was amazing. The birdlife around the lake was prolific, not my thing particularly but apparently the area attracts visitors for that purpose. It is a bit off the tourist track but is within striking distance of Da nang if you are visiting Hue or Hoi An.

Apart from that experience, I have never seen other elephant during many visits to Vietnam.