The following are private buses that operate in and out of Paknam City.

Paknam to Si-iam – This is a private bus that goes from Paknam to Si-iam. Most private buses don’t have number nor any English. There is a number on the side that says “1196” which seems consistent for this colour scheme. On the side of the bus it has the company name and the start and end destination. It doesn’t say which route it takes though. Si-iam is the name of the temple at the point where Srinakarin Road crosses Bang Na-Trad Highway. This bus goes via Srinakarin Road. You can take this bus to go to Tesco Lotus Plus, Foodland, Makro and Carrefour Srinakarin.
Paknam to Si-iam – This next one is also Paknam to Si-iam. The number on the side says “1141” which again seems consistent. However, this goes via Samrong along Sukhumwit Road. You would catch this bus if you wanted to go to Carrefour Samrong,  Imperial World Samrong, BITEC and Central City Bang Na. Unless you know already, there is no indication which road it takes to Si-Iam.
Paknam to Si-iam – This next bus is also Paknam to Si-iam and is a different company. The bus number is clearly “365”. In the window there is a sign in Thai that says the route it takes: Paknam, Samrong, Bang Na and Si-iam. So this one also goes past Central City Bang Na.
Paknam to Bang Pakong – Confusingly, this green bus is also number “365” and is owned by the same company. However, at the top in Thai it says Paknam to Bang Pakong. At the bottom of the windscreen it gives you an indication of the route it takes. Samrong, Bang Na, Bang Phli and Hua Chiew. This takes the same route as the other “365” bus but just goes further. You would catch this bus for Central City Bang Na and any destination along the Bang Na-Trad Highway as far as Bang Pakong River. You probably could catch this bus to go and see the dolphins when they are visiting the estuary here.
Paknam to Klong Dan – This bus has the number 1140 on the side and goes to Klong Dan. It takes the old Sukhumwit Road from Paknam and follows the coastline to Klong Dan. You could take this bus for Ancient Siam and Bang Pu Seaside Resort. It will also pass the Samut Prakan Central Prison. There is also a large songtaew that goes on this route from Paknam.
Paknam to Phra Pradaeng – This bus has the number 1286 on the front. It goes up Sukhumwit Road towards Samrong but turns off early to go down Pu Chao Saming Phrai to the end of the road. If you want to continue to Phra Pradaeng City then you need to cross the river on the ferry.
Paknam to Ram Khamhaeng University 2 – This bus has the number 1141 on the front. At first glance I thought it was going to Rama 2. But it is really going to Ram Khamhaeng University 2 in Bang Na. It heads north from Paknam up Sukhumwit Road towards Samrong. At the Bang Na Intersection, it turns right and heads along the Bang Na-Trad Highway. It passes Central City Bang Na and crosses over Srinakarin Road. It then turns off to the university shortly before the Kanchanaphisek Outer Ring Road.