Heartpia Atami

The onsen has all the amenities you'd need. There's a flat rate for the day, with lunch and towel rental included.

A heads-up for anyone with tattoos: tattoos aren't allowed here.

The breakfast had plenty of options, and I especially liked the different salts for ham and eggs, including flying fish stock salt. The staff were lovely, and there's a free shuttle from Atami Station several times a day. This seems ideal for travelling alone. Single rooms are available, unlike the large, expensive Japanese-style rooms solo travellers often end up with at hot spring inns. The price probably varies by season, but when I went it was about the same as a business hotel, and you still get an open-air hot spring bath. My room had an ocean view, a clean toilet and shower, and lots of space. I also appreciated the bath basket, roomy bathroom, soft paper towels, and towel rack. The facilities were better than at a business hotel. Definitely worth checking out.

The large public bath was roomy and very satisfying, and the sauna was spacious, hot, and well equipped. The food was tasty Japanese fare with a simple flavor. The place feels more like a traditional inn than a hotel, with a distinctly Japanese atmosphere and bright spaces. The rooms had amazing views. Since it's built on a cliff, the entrance sits about halfway down from the parking lot, so you'll need the elevator to reach lower floors such as the first or second. The key is a regular old-fashioned one, not a card.