I visited the Aquarium of the Bay, located at Pier 39 in San Francisco, about 3-4 years ago, and had fond memories of it. This aquarium provides a educational, and fun introduction to the rich aquatic life inhabiting the San Francisco Bay. The highlight of the visit was the clear, 150 ft tunnels providing wonderful, majestic views of underwater creatures like sharks, fish, rays, and other indigenous animals. Each visitor is provided with a tape player and headset, serving as a virtual tour guide. At $14 per adult (and $7.50 per child), it serves as a great, nearby alternative to visiting the Monterey Bay Aquarium (although I believe that a trip to the Monterey Bay Aquarium would provide a much deeper and richer experience).