Not for the claustrophobic, the Narusawa Hyōketsu (ice cave) was formed by lava flows from an eruption of Mt Fuji in 864. It takes about 10 minutes to walk through to the end to see the ice pillars, which are at their peak in April (no ice from September to December). Only the blue-line sightseeing bus stops here.
Narusawa Hyōketsu
Fuji Five Lakes