Not far from Vang Veng, you can visit four caves in a row. In the first one, you can even go tubing. In the other two, you can walk quite a way inside (with good footwear! The floors are wet and slippery; headlamps can be rented there) until it gets increasingly narrow and low. There are stalactites and stalagmites. In the fourth cave, there's a stalactite that looks like an elephant. Easily accessible from Vang Veng by tuk-tuk.