The entrance to the lagoon is, of course, shallow. There are also some rocks in the sand so care needs to be taken navigating the rocks while dealing with the waves. The entrance is protected on its northern side by Narrabeen Head but is exposed to swells from the east to the south (well SSE). The lagoon is large and the entrance narrow and shallow so the tidal flow is strong. This is not a passage for novice kayakers and it will pay to stow all gear securely.
There are many lauch spots within the lagoon, which is a fine fishing destination in its own right. The best launch spot to exit the lagoon is a car park just south of the Ocean St bridge (Warringah Council pay parking but limited free parking is available on Ocean St). A bit further upstream on the north side and adjacent to the caravan park is a small concrete ramp with free parking (be careful of the anglers wading the flats to access a very productive hole)