Photography and information from crochet.me:

Eyelets separate gentle ripples of textured crochet in an easily memorized lace pattern for a scarf that dresses up jeans or a dress. Modify this simple accessory for a wider or longer scarf.

Designer: Ruth Garcia-Alcantud
Finished Size: 6” wide and 60” long.
Yarn: South West Trading Company Jezebel (100% merino; 328 yd 300 m/1¾ oz 50 g): #692, 2 skeins.
Hook Size: E/4 (3.5 mm). Adjust hook size if necessary to obtain correct gauge.
Notions: Yarn needle; blocking equipment.
Gauge: 19 sts and 16 rows = 4” in river patt.