Name of old animated film?

I can only vaguely remember 2 scenes. It was a lady swimming in the water and the cameras pont of view was from underneath her as she swam by. Second thing I recall is that she needed to cross a river of lava or maybe acid and the only way across was on small boat that wasn't affected by the river but it was guarded by this grotesque slug creature. The creature said that she could take the boat in exchange for a kiss. She reluctantly agrees but the creature basiclly shoots out its elongated tongue down her throat and gives her a sloppy smooch much to her disgust. I believe she gets to use the boat and that's all I can recall. Over 10 years plus, any ideas?