Agistri's center is dense with pine forest — a rarity in the sun-bleached Saronic islands — and the trees run nearly to the water's edge in places. Walking the trail toward Mariza beach in the south, you pass through stands of pine that open suddenly onto coves of clear turquoise water. Wild cyclamen, thyme, and caper bushes push through the forest floor. The rocky eastern coast, exposed to the prevailing winds, serves as a breeding ground for swifts, while chukar partridges rustle through the undergrowth. In 2011, the Prefecture of Piraeus and the National Technical University of Athens formally recognized Agistri as a "green island" — an acknowledgment of what any visitor quickly senses: the balance between tourism and nature here remains, for now, carefully maintained.

The island's 1,131 residents (as counted in the 2021 census) live mostly in Megalochori, the main village — also called Milos — where the majority of daily life unfolds at the pace that small Aegean communities set for themselves. Skala, a twenty-minute walk along the coastal road, handles the island's tourist infrastructure: hotels, restaurants, the ferry dock. Limenaria, tucked on the island's far side, is the quietest of the three, barely touched by the summer visitors who fill the beaches of Skala and Megalochori. The Church of Agioi Anargyroi in Skala is the island's most photographed building, its white walls and blue dome rising from the harbor front. Between the villages, a bus and taxis connect the dots — the island is too small to need more.

Agistri's population arrived relatively recently by Greek standards. The island was settled by Arvanites — Greek Orthodox communities of Albanian origin who spread through much of mainland Greece and the Saronic islands — likely beginning in the late 17th century. The Arvanite community still inhabits the island, a continuous thread connecting the present to those early settlers. The Arvanite language, Arvanitika, has largely faded from daily use across Greece, but the cultural identity persists. Agistri's community is one of many such settlements in the Saronic region where Arvanite roots shaped the character of the place in ways not always visible to visitors but deeply felt by those who live there.

The beaches that draw visitors range from the popular sandy stretches at Aponissos and Dragonera on the western coast — where the calm waters face Aegina — to the more secluded Skliri and Halikiada in the east. Halikiada has long been associated with naturism. The island's history of free camping in the pine forests has wound down due to fire hazard regulations, but the spirit of low-key, informal tourism remains Agistri's calling card. An hour by ferry from Piraeus, it offers an escape that requires no planning and no pretense. Agriculture also contributes to the local economy, though tourism long ago became the primary industry. The peacocks — feral descendants of introduced birds — wander between the villages and the forest edge with the unhurried confidence of animals that have never been afraid of people.