Nature in Istanbul starts at the water. The Bosphorus is not a sight but a working strait, with a current, dolphins and migrating birds: in spring and autumn hundreds of thousands of storks and raptors pass directly over the city, along one of the three great flyways of Eurasia. Seeing the shoreline from the water rather than from the road changes how the city reads.

The Princes' Islands lie ninety minutes away by ferry and have no cars. On Büyükada and Heybeliada you move by electric cart or on foot, through pine woods up to the monasteries on the hills; they are crowded in summer and nearly empty on an off-season weekday. The Belgrade Forest to the north is the other way out: old beeches, Ottoman aqueducts, and trails the city uses itself.

Further out, an outdoor day from Istanbul means Lake Sapanca and Maşukiye with their waterfalls and trout farms, paragliding above the Black Sea coast, or walking routes in the surrounding hills. Nature tours run all year, but April to June and September to October are the good windows: mild, clear, and without the humidity that makes high summer here heavy. Ask whether ferry tickets and the island transfer are included, and check the last return sailing before planning a long day on the islands.