Underway: NYC Subway Transit is a subway app designed for iPhone users. It provides real-time arrival information and service status for New York City subway stations. With a user-friendly interface, this app allows users to easily view arrivals for any subway station by tapping directly on an official MTA subway map.

One of the key features of Underway is its offline optimization. Users can access the subway map and the most recent data from the server even when they are underground, ensuring a seamless experience during long subway rides. The app also offers real-time data on incoming trains, allowing users to compare train options before making their choice.

In addition to providing arrival information, Underway also alerts users about service disruptions affecting subway lines. It features closed station indicators and does not require GPS, saving battery life. Upon launch, the app can instantly locate nearby stations, although this feature is optional with GPS.

Underway is supported by ad revenue and offers in-app purchases. It allows users to share links to specific trains with friends, enabling them to track their arrival in real-time.

Overall, Underway: NYC Subway Transit is a comprehensive subway app that provides essential information for New Yorkers on the go. Its user-friendly interface and offline optimization make it a valuable tool for navigating the city's subway system.