From 1977 a second Zoo service was introduced by projecting service 15A (Bispham-Hospital) the short distance to the Zoo. This gave access from much of North Shore plus the town centre and operated every 30 minutes all year round. In 1982 the 15A was diverted to Staining and Grange Park with the Hospital - Zoo section tagged on to routes 23/23A (Midgeland Rd/South Pier-Hospital) during the summer. A 15 minute weekday and 30 minute Sunday service was provided.
At deregulation the 21 continued but the 23/24/25 replaced routes 23/23A. They did not serve the Zoo in 1987 but did from 1988 to circa 1993. Fylde briefly served the Zoo with route 4 (Cleveleys-Lytham St. Annes) passing the pedestrian entrance on East Park Drive from 1989 to 1991 when Carriages took over. Next came service 3 (Poulton-St. Annes) which used route branded Atlanteans and served the main entrance but only ran March to September 1992. Finally another route 3 Blackpool-Village Hotel (now the Devere) was introduced in 1993 and in August was re-routed to serve the Zoo entrance. It ceased at the end of November.
Other bus routes have run past the pedestrian entrance including route 53 started by Easyway in March 1986, taken over by Blackpool in 1989 (and run to 1991), similar route 53A started by Town Bus from 1990 to 1995, Fylde 1995, Phoenix North West 1996-2001, BTS in 2001 when it was replaced and short lived service 9 (Poulton to Mereside). Lifestyle Line 16 currently serves this route.
Throughout this mayhem, route 21 continued largely unchanged. A basic 40 minute service with extras as required and often providing a 20 minute service, sometimes a 10 minute one. Usually operated by Atlanteans, the odd crew bus appeared using staff on stand-by. Open Top PD2 532 - ex Eastbourne - put in occasional appearances from 1989 and Routemasters ran quite regularly in 1996. The take-over of Fylde saw the 21 transferred there when for part of 1996, and they ran the whole service for 1997 on an extended Pleasure Beach-Tower-Zoo basis every 20 minutes using 3 buses. 1998 saw a 20 minute Tower-Zoo service operated sometimes from Squires Gate and sometimes from Rigby Road, the closure of Squires Gate in April 1999 putting paid to this swapping.
2001 saw the start of the City Sightseeing Blackpool tour which ran Pontins-Tower-Zoo-Waterloo Road -Pontins. Its first year was quite poor, so for 2002 the Tour and the 21 were merged running Pontins-Tower-Zoo in both directions. A half hourly service ran using the City Sightseeing open top Metrobuses as a joint venture with Ensign (the brand owners). This continued until 2005 when the 21 ceased.
The 2006 season saw service 20 take over. This had run for several seasons from Marton Mere to Town Centre and was now extended to the Zoo via the 21 route. It used 3 buses on a half hourly basis. The open toppers had moved onto Line 1, though they were not a success. For 2007 a totally revised City Sightseeing route 20 was started -by now the tour was a 100% Blackpool Transport operation under license rather than the joint venture. Buses now ran from Pontins via the Promenade to Tower, up Hornby Road, to Stanley Park, round the Cricket Club access road, up North Park Drive and Woodside Drive to the Zoo then back past the Model Village, East Park Drive, South Park Drive and Preston New Road to Marton Mere. 3 buses are required (every 30 minutes) and the Metrobuses have been replaced by City Sightseeing ex London Olympians.