The Río Tempisque is spanned by the Puente de Amistad con Taiwan, a suspension bridge whose construction was a gift from the Taiwanese government. On its west bank, Highway 18 continues 15 kilometers to a T-junction with Highway 21 at Puerto Viejo; the town of Nicoya [1], the regional capital, is 15 kilometers north of the junction (Highway 21 loops north via Santa Cruz [2] and Filadelfia to reconnect with Highway 1 at Liberia [3]).
Tempisque Eco-Adventures & Canopy Tour (tel. 506/2687-1212, ecoadventures [at] racsa [dot] co [dot] cr), four kilometers west of the bridge, has a canopy tour ($40) and offers boat trips to Palo Verde National Park [4] at 9:30 a.m. and 1 p.m. daily ($45).
Links:
[1] http://www.moon.com/destinations/costa-rica/the-nicoya-peninsula/highway-2-santa-cruz/nicoya
[2] http://www.moon.com/destinations/costa-rica/the-nicoya-peninsula/highway-2-santa-cruz/santa-cruz
[3] http://www.moon.com/destinations/costa-rica/guanacaste-and-the-northwest/liberia-and-vicinity/liberia
[4] http://www.moon.com/destinations/costa-rica/guanacaste-and-the-northwest/canas-and-vicinity/palo-verde-national-park