Visit to the Cave of the Lakes at Kastria, then a one-way hike of about 6.3 km and 2-2.5 hours, mostly downhill on easy ground with views of Helmos, to Planitero and the Aroanios springs for a meal before heading back. +114/-336 m, grade easy 1/5, ages 8+ (children with an adult). Meet 06:45, coach leaves 07:00 from the Museum of Contemporary Art (Syngrou-Fix metro), then Palataki 07:20, Elefsina (Praktiker-BIEX) 07:30 and Isthmus (Kanali cafe) 08:10; back about 20:30. €40, €25 deposit. Not included: cave entry (€7 group ticket, normally €9) and food at Planitero. Includes the coach, experienced first-aid certified guides, group first-aid kit, civil liability insurance and VAT. Book and pay online on trekkers.gr; bookings are per person. Sold out on the organizer's site as of 18 October 2026.