Miho peninsula is a straight drive out on seaside route 150, heading south and then east from Shizuoka City. The new road will curve to the left after several kilometers and there will be a three-way stoplight. Turn right and you will pass through a more urban area with Tokai University on your right. Drive all the way to the end of the main road. You'll pass a soccer pitch and harbor entrance on your left, and straight ahead at the last bend in the road is the Tokai University aquarium and natural history museum.
Admission to the aquarium is 1500 yen for adults, or 1800 yen inclusive of the natural history museum. Children are 750 yen and 900 yen likewise. I love visiting aquariums, and have been to many around the world. They always seem a little pricey, perhaps because upkeep of the animals is day-over-day expensive. Beyond the smaller, well-done exhibits at this aquarium, the large, central tank contains some impressive sharks and rays.
The interactive natural history museum is certainly worth the extra 300 yen, especially if you are in the cerebral mood, and the dinosaur-bones exhibit leads you to reflect on what tremendous animals they were. After your tour, you can visit the refreshment stands and then walk a few steps over to the beach.
Japan is a maritime nation with quite a few people engaged in water activities and Miho can be a regular free-for-all on a summer weekend with: windsurfers, kayakers, dinghies, divers, fishermen, waders at the beach, an occasional yacht anchored offshore, and jet skis in the water. Not to mention a couple visits by the ferry, kids jumping off that dock, and the presence of big ships out in the channel. I have had a few collisions, most recently with a fishing net- I thought my fin had struck concrete- and I once witnessed a harrowing wreck between a windsurfer and a dinghy. If you decide to enter the water, you need to stay alert.
Evenings on Miho are pleasant and non-summer months are much quieter. The tip of the peninsula points due north and you can easily walk around it to the Suruga bay side, which is not protected, and has bigger waves and stronger currents. On a clear day, nearby Mount Fuji is grand.