A stairwell leads up to the cave, and a variety of plants grows around the entrance of the cave (including a Nirnroot down by the water).
Inside the cave is a moderately-sized band of vampires, with the telltale sign of several coffins present (common in vampire caves). The loot here mainly comes from defeating the vampires and increases in quality and value as the Hero levels up.
The vampire matriarch/patriarch usually carries an enchanted two-handed weapon. To get to the last treasure hoard, defeat the patriarch or matriarch in the room with the coffin and approach a suspicious corner, and it will open up to reveal some gold coins or a soul gem.