4 October 2023, Resen, 39.18km
Majcka Poca 1500 den [R486]

In tiny Kosel, population 586, we were lured into an attractive _Ресторан_ (restaurant) for a creamy cappuccino. On the sidewalk beside a clear shallow stream was an information board that told of a nearby geothermal feature. After our coffee, we backtracked briefly down the road we had cycled from Ohrid in search of the turnoff to the "volcano". The sign had fallen partially into the bushes, but our noses told us we were on the right track. 
"Duvalo is an active geothermal surface feature [resembling] a miniature crater with a diameter of 50 cm and depth of 30 cm. Gaseous carbon dioxide and sulfur dioxide are released from the hole. It represents the last traces of historically significant volcanic activity in the area. During the Ottoman Empire it was used to mine sulfur." 
There was not much to see which probably explains why the signage and fence have fallen into disrepair. I thought this phrase I read somewhere best captured the feature: "volcanic exhalation". 
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We had a superb ride through hilly terrain. Our first 24km were on an incline, gaining us over 520m in elevation. Then we dropped down the other side of the mangled pass, past orchards of red apples ripe for picking, to the small town of Resen and beyond to our accommodation. On the outskirts of Resen, we stopped at Restaurant Classic for a late lunch of Shopska salad (cucumber, tomato and grated white brine cheese) and bean soup.
The last 5 or 6km of our climb were hard work but not so steep they required a percentage warning. Annoyingly, we were accompanied on this section by dozens of persistent midgies that flew beside our handlebar bags from where they launched soft attacks into our mouths and noses and eyes. Horrid! On the long downhill after the summit, we bid them farewell!