Heading south from Matsuzaki, another 10 km or so brings you to Hagachizaki [波勝崎], a habitat for macaques on the coast. Turn right off the main road when you see the colorful sign and wind your way down.
Watch for the macaques, as they generally roam free here. Once as we drove down to the visitors' building, there was one sitting yoga-like, perhaps unbeknown, atop the car in front of us. The resident primates' hi-jinks are amusing, and their sun-splashed, seaside home idyllic.
About 12 km further on, turn right off the main road 136 onto the smaller loop road 16 to visit Irozaki [石廊崎], the southern tip of Izu. After 7.5 km, you will see a pull-out with a gift shop on your right. You can take the short hike up the hill to your left for splendid views, or just enjoy them from the back of the parking lot.
Down below in summer months, you may notice quite a few snorkelers, and then you may wonder how you can get down there too. Simply drive back down the road a couple kilometers and you will turn left to go down to the coast at Hirizohama [ヒリゾ浜]. Here boats regularly transport snorkelers to and from the site. It takes about 5 minutes. The snorkeling is top-notch, teeming with fish, and even includes a few colorful hard corals. Be wary of moving out into the channel too far as the current can be quite strong.
Drive northeast from Irozaki about 5.5 km and you will see Yumigahama [弓ヶ浜] on your right. As the name implies, this beach is bow-shaped. The cove is protected and an excellent place to take small children. For the more adventurous, there is excellent snorkeling around a large rock just below the surface a few tens of meters to the left beyond the beach area.
The large hotel facing the beach has traditional rooms and food and there are hot springs inside. Call far in advance if you wish to make a reservation there for the summer months, for the east side of Izu is more crowded than the west side due to the influx of summer vacationers from the Tokyo area. Note that parking in the summer season can be a hassle here.
Continue north about 1.5 km to return to the main road 136, turn right, and another 8 km brings you to the town of Shimoda [下田]. Just before Shimoda, on your right, are the best surfing spots on Izu. They are not visible from the road, so you must turn off and creep down to them on side roads. The first is Iritahama [入田浜] which faces more direct ocean and can have huge swells. The next is Tatado [多ヶ戸], a picturesque beach, slightly more protected and with a sandy bottom. If you skirt the south edge of Shimoda and drive out on the small peninsula, there is a nice little aquarium there that is certainly worth the visit.