Why this axis: canopy walk, not island parks
Southern Ridges spends distance and humidity for canopy views; USS / Oceanarium spends tickets and queues for rides. Both sit south, but the energy budgets cancel — same day collapses one of them.
Common mistakes: afternoon start, then still boarding the island
Start HortPark / ridge segments at dawn or morning — noon heat multiplies. After Henderson Waves photos, close at HarbourFront; cable car and Express wait for a real Sentosa day.
Who it suits
Suits: walkers with grip shoes, ~2 L water, chasing an urban green corridor. Strollers and suitcase travellers: Bay flat paths or Botanic main walks instead.