Shuzenji Onsen,a dense warren of inns and ryokans on both sides of a small river, is one of the oldest and most famous onsens in the Izu peninsula, but unfortunately has precious little to recommend it. It is so mobbed with bus tours and sightseers that one can't really feel too relaxed, and the scarcity of parking spaces make it almost impossible to stop. Worst, many shopkeepers aren't friendly.
However, Hakonoyu, the main public bath, is a fine hinokiburo, and at only 350 yen it is fine soak, one of the least expensive ways to experience the fragrance of hinoki wood (Japanese cypress) without a ryokan overnight stay. Yu no Hana (Water Flowers) are the whitish things floating in the water. Resembling wet tissue, Yu no Hana are nothing to be worried about. Onsen newcomers often mistakenly think that Yu no Hana mean the bathwater is dirty, yet just the opposite is true: they are an often prized indication of onsen water quality.
Most people come here by bus but even so, Shuzenji Onsen might just be better off avoided. Quieter, more peaceful, and friendlier spots are nearby, and in many ways Shuzenji epitomizes the worst of the worst in onsens: places that survive by virtue of the bus tours alone, with precious little redeeming. Bathgoers not staying at a ryokan will have few options once they've visited Hakonoyu. Lastly, Tokko no Yu, the famous rock which spouted forth onsen water when struck with a piece of iron...was moved (of all things!) as of April 2009. Lo and behold, it is a carefully constructed cement island...not a genuine, original rock or crag. So that's yet another reason why Shuzenji really doesn't cut the mustard. Why is it in here? Again, Hakonoyu, fragrant and simple, is a nicely done public bath that won't disappoint people already stopping by.