Sentosa’s headline attractions: Universal Studios (park opens about 10:00am) or S.E.A. Aquarium (usually 10:00am–6:00pm). Choose based on interest—family rides vs marine exhibits.
Walk the compact historic core—see Christ Church, the red Dutch Square buildings and the A'Famosa fort remnants (sites generally open daily during daylight).
Famous Hindu shrine with the giant golden Murugan statue and cave temples; open 7:00am–9:00pm—late afternoon light is pleasant and less crowded than morning.