Wat Arun is almost directly opposite Wat Pho, so it is very easy to get to. From Sapphan Taksin boat pier you can take a river boat that stops at pier 8. From here a small shuttle boat takes you from one side of the river to the other for only 3 baht. Entry to the temple is 100 baht. The temple is open daily from 08:30 to 17:30.