A police spokesman said they were called to John Wilson Ocean Dr, in St Kilda, after two men threw one of the electric scooters into the sea just before 10pm.
Shortly after, officers were sent to the Esplanade, St Clair, following a report of five men hurling another Lime scooter and a push bike into the ocean opposite the closed Pier 24 restaurant, the spokesman said.
This Lime and the bicycle were recovered, but the fate of the first scooter was unknown.
Unconfirmed reports from earlier in the day suggested several more Limes had met a watery end at St Clair Beach.