Mumbai Metro Line Three, also known as the Aqua Line, is advancing plans for an extensive underground pedestrian network linking major locations in south central Mumbai. The proposed scheme would create a series of subterranean walkways branching from key stations to nearby office complexes, public spaces and transport hubs. Mumbai Metro Rail Corporation Limited (MMRCL) has invited bids for design and project management consultancy services to build the tunnels and associated station vestibules. The network is expected to span close to three km in total. Two tunnels are proposed to originate from the Science Centre station. One corridor would run approximately one point one km towards the Worli promenade through the Mahalaxmi Racecourse area, while a 500-metre link would connect the station with the Nehru Planetarium. Separately, a longer underground passage of around one point four km is proposed from the Bandra Kurla Complex (BKC) station to the planned high speed rail terminal near the Diamond Bourse. The layout aims to provide direct access to commercial buildings and public destinations. Planners envisage the links will allow commuters to move seamlessly between mass transit and workplaces without surface congestion. The corridors are intended to integrate with transit oriented development policies by encouraging developers to physically connect buildings to nearby metro stations. Urban mobility experts cited in preliminary documents suggested such infrastructure could transform movement patterns across dense business districts. The proposals also aim to improve pedestrian safety and shelter from monsoon conditions. Implementation will depend on contract awards and detailed design work to address construction complexity under existing structures and open spaces. MMRCL will manage interfaces with municipal authorities, utilities and property owners to align tunnelling with urban planning objectives. Project proponents anticipate that, once complete, the subterranean links will change commuter flows and support broader efforts to reduce surface traffic in the city centre. Timelines remain subject to procurement outcomes and regulatory clearances.