"The Grotto" is the unofficial title for a collection of shacks and bamboo tables on the river that doesn't actually have a name. It's a refreshing alternative to Riverside for watching the sun go down and and prices are about as cheap as you'll find in any other nameless streetside bar. There's also a kitchen that does all your favorites (graphrao, kai jiew, pad thai, etc). It's a bit difficult to find - you have to turn into the entrance to the walking bridge, go alongside it and turn right when you hit the river. There's bike parking down there but it gets nasty in the rainy season if the whole thing isn't flooded. Bring mosquito repellent and a fishing rod -- after watching the sunset, you can continue on there or move on to listen to live music over at Riverside.