line up ==> to describe the line a breaking wave follows. The "line up" is used to decribe the rideable part of the wave that a surfer will follow.

rip current => A channel of water, or a current, heading out to sea. Often simply known as a rip. Recognizeable by choppy whitewater and sea junk going out to sea.

http://en.wiktionary.org/wiki/Appendix:Glossary_of_surfing

Rip current = 離岸流;離岸激流
breaking wave - 碎波

（图）碎波带_碎波带图片_图片百科 - [ Translate this page ]碎波带波浪碎波后即扑向海岸，从碎波线至海岸摊线之范围称为碎波带，若在碎波带内兴建海岸结构物，设计时应以碎波波浪之波力计算结构物所承受之外力。 ...
tupian.hudong.com/a3_03_20_01300000290862122871205076486_jpg.html - Cached

國立教育資料館 碎波型態特性之探討, Characteristics of Breaking ... - [ 转为简体网页 - Translate this page ]碎波型態特性之探討= Characteristics of Breaking Waves on Sloping Beaches. 點閱：120; 推薦：0; 評論：0; 引用：0; 轉寄：0. 作者：施佳利, 林朝福; 出版地：台中 ...
data.nioerar.edu.tw/ct.asp?xItem=149224&ctNode=209&mp... - Cached

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Note added at 19 hrs (2009-12-20 01:42:49 GMT)
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Surf zone - Wikipedia, the free encyclopediaAs ocean surface waves come closer to shore they break, forming the foamy, bubbly surface we call surf. The region of breaking waves defines the surf zone.
en.wikipedia.org/wiki/Surf_zone - Cached - Similar

line-up - 1. the place just beyond the impact zone where you wait to catch waves. 2. the place where the surfers are sitting. 3. the place where the waves are breaking 4. a marker on the beach used to position off of
http://www.krankykids.com/research/surf_slang.html
http://www.girls-who-surf.com/surfer-lingo.html
http://www.gowersurfing.co.uk/faq_surf_talk.html

from the definitions above, line-up == surf zone (碎波带)


In the line up = 在碎波带内